diff --git a/libp2p.nimble b/libp2p.nimble
index 106cd59d5..ef37b2dca 100644
--- a/libp2p.nimble
+++ b/libp2p.nimble
@@ -16,11 +16,13 @@ requires "nim >= 1.2.0",
          "secp256k1",
          "stew >= 0.1.0"
 
-proc runTest(filename: string, verify: bool = true, sign: bool = true) =
+proc runTest(filename: string, verify: bool = true, sign: bool = true,
+             moreoptions: string = "") =
   var excstr = "nim c --opt:speed -d:debug --verbosity:0 --hints:off"
   excstr.add(" --warning[CaseTransition]:off --warning[ObservableStores]:off --warning[LockLevel]:off")
   excstr.add(" -d:libp2p_pubsub_sign=" & $sign)
   excstr.add(" -d:libp2p_pubsub_verify=" & $verify)
+  excstr.add(" " & moreoptions & " ")
   if verify and sign:
     # build it with TRACE and JSON logs
     exec excstr & " -d:chronicles_log_level=TRACE -d:chronicles_sinks:json" & " tests/" & filename
@@ -48,11 +50,22 @@ task testpubsub, "Runs pubsub tests":
   runTest("pubsub/testpubsub")
   runTest("pubsub/testpubsub", sign = false, verify = false)
 
+task testfilter, "Run PKI filter test":
+  runTest("testpkifilter",
+           moreoptions = "-d:libp2p_pki_schemes=\"secp256k1\"")
+  runTest("testpkifilter",
+           moreoptions = "-d:libp2p_pki_schemes=\"secp256k1;ed25519\"")
+  runTest("testpkifilter",
+           moreoptions = "-d:libp2p_pki_schemes=\"secp256k1;ed25519;ecnist\"")
+  runTest("testpkifilter",
+           moreoptions = "-d:libp2p_pki_schemes=")
+
 task test, "Runs the test suite":
   exec "nimble testnative"
   exec "nimble testpubsub"
   exec "nimble testdaemon"
   exec "nimble testinterop"
+  exec "nimble testfilter"
 
 task examples_build, "Build the samples":
   buildSample("directchat")
diff --git a/libp2p/crypto/crypto.nim b/libp2p/crypto/crypto.nim
index a6a291e4e..820bde77d 100644
--- a/libp2p/crypto/crypto.nim
+++ b/libp2p/crypto/crypto.nim
@@ -8,29 +8,79 @@
 ## those terms.
 
 ## This module implements Public Key and Private Key interface for libp2p.
-
 {.push raises: [Defect].}
+from strutils import split, strip, cmpIgnoreCase
 
-import rsa, ecnist, ed25519/ed25519, secp, bearssl
-import ../protobuf/minprotobuf, ../vbuffer, ../multihash, ../multicodec
-import nimcrypto/[rijndael, blowfish, twofish, sha2, hash, hmac, utils]
-import ../utility
-import stew/results
-export results
-
-# This is workaround for Nim's `import` bug
-export rijndael, blowfish, twofish, sha2, hash, hmac, utils
-
-from strutils import split
+const libp2p_pki_schemes* {.strdefine.} = "rsa,ed25519,secp256k1,ecnist"
 
 type
   PKScheme* = enum
     RSA = 0,
     Ed25519,
     Secp256k1,
-    ECDSA,
-    NoSupport
+    ECDSA
 
+proc initSupportedSchemes(list: static string): set[PKScheme] =
+  var res: set[PKScheme]
+
+  let schemes = split(list, {',', ';', '|'})
+  for item in schemes:
+    if cmpIgnoreCase(strip(item), "rsa") == 0:
+      res.incl(PKScheme.RSA)
+    elif cmpIgnoreCase(strip(item), "ed25519") == 0:
+      res.incl(PKScheme.Ed25519)
+    elif cmpIgnoreCase(strip(item), "secp256k1") == 0:
+      res.incl(PKScheme.Secp256k1)
+    elif cmpIgnoreCase(strip(item), "ecnist") == 0:
+      res.incl(PKScheme.ECDSA)
+  if len(res) == 0:
+    res = {PKScheme.RSA, PKScheme.Ed25519, PKScheme.Secp256k1, PKScheme.ECDSA}
+  res
+
+proc initSupportedSchemes(schemes: static set[PKScheme]): set[int8] =
+  var res: set[int8]
+  if PKScheme.RSA in schemes:
+    res.incl(int8(PKScheme.RSA))
+  if PKScheme.Ed25519 in schemes:
+    res.incl(int8(PKScheme.Ed25519))
+  if PKScheme.Secp256k1 in schemes:
+    res.incl(int8(PKScheme.Secp256k1))
+  if PKScheme.ECDSA in schemes:
+    res.incl(int8(PKScheme.ECDSA))
+  res
+
+const
+  SupportedSchemes* = initSupportedSchemes(libp2p_pki_schemes)
+  SupportedSchemesInt* = initSupportedSchemes(SupportedSchemes)
+  RsaDefaultKeySize* = 3072
+
+template supported*(scheme: PKScheme): bool =
+  ## Returns true if specified ``scheme`` is currently available.
+  scheme in SupportedSchemes
+
+when supported(PKScheme.RSA):
+  import rsa
+when supported(PKScheme.Ed25519):
+  import ed25519/ed25519
+when supported(PKScheme.Secp256k1):
+  import secp
+
+# We are still importing `ecnist` because, it is used for SECIO handshake,
+# but it will be impossible to create ECNIST keys or import ECNIST keys.
+
+import ecnist, bearssl
+import ../protobuf/minprotobuf, ../vbuffer, ../multihash, ../multicodec
+import nimcrypto/[rijndael, twofish, sha2, hash, hmac, utils]
+import ../utility
+import stew/results
+export results
+
+# This is workaround for Nim's `import` bug
+export rijndael, twofish, sha2, hash, hmac, utils
+
+from strutils import split
+
+type
   DigestSheme* = enum
     Sha256,
     Sha512
@@ -39,29 +89,49 @@ type
 
   PublicKey* = object
     case scheme*: PKScheme
-    of RSA:
-      rsakey*: rsa.RsaPublicKey
-    of Ed25519:
-      edkey*: EdPublicKey
-    of Secp256k1:
-      skkey*: SkPublicKey
-    of ECDSA:
-      eckey*: ecnist.EcPublicKey
-    of NoSupport:
-      discard
+    of PKScheme.RSA:
+      when PKScheme.RSA in SupportedSchemes:
+        rsakey*: rsa.RsaPublicKey
+      else:
+        discard
+    of PKScheme.Ed25519:
+      when supported(PKScheme.Ed25519):
+        edkey*: EdPublicKey
+      else:
+        discard
+    of PKScheme.Secp256k1:
+      when supported(PKScheme.Secp256k1):
+        skkey*: SkPublicKey
+      else:
+        discard
+    of PKScheme.ECDSA:
+      when supported(PKScheme.ECDSA):
+        eckey*: ecnist.EcPublicKey
+      else:
+        discard
 
   PrivateKey* = object
     case scheme*: PKScheme
-    of RSA:
-      rsakey*: rsa.RsaPrivateKey
-    of Ed25519:
-      edkey*: EdPrivateKey
-    of Secp256k1:
-      skkey*: SkPrivateKey
-    of ECDSA:
-      eckey*: ecnist.EcPrivateKey
-    of NoSupport:
-      discard
+    of PKScheme.RSA:
+      when supported(PKScheme.RSA):
+        rsakey*: rsa.RsaPrivateKey
+      else:
+        discard
+    of PKScheme.Ed25519:
+      when supported(PKScheme.Ed25519):
+        edkey*: EdPrivateKey
+      else:
+        discard
+    of PKScheme.Secp256k1:
+      when supported(PKScheme.Secp256k1):
+        skkey*: SkPrivateKey
+      else:
+        discard
+    of PKSCheme.ECDSA:
+      when supported(PKSCheme.ECDSA):
+        eckey*: ecnist.EcPrivateKey
+      else:
+        discard
 
   KeyPair* = object
     seckey*: PrivateKey
@@ -84,11 +154,6 @@ type
 
   CryptoResult*[T] = Result[T, CryptoError]
 
-const
-  SupportedSchemes* = {RSA, Ed25519, Secp256k1, ECDSA}
-  SupportedSchemesInt* = {int8(RSA), int8(Ed25519), int8(Secp256k1),
-                          int8(ECDSA)}
-
 template orError*(exp: untyped, err: untyped): untyped =
   (exp.mapErr do (_: auto) -> auto: err)
 
@@ -106,77 +171,162 @@ proc newRng*(): ref BrHmacDrbgContext =
     return nil
   rng
 
-proc random*(
-    T: typedesc[PrivateKey], scheme: PKScheme,
-    rng: var BrHmacDrbgContext, bits = DefaultKeySize): CryptoResult[PrivateKey] =
+proc random*(T: typedesc[PrivateKey], scheme: PKScheme,
+             rng: var BrHmacDrbgContext,
+             bits = RsaDefaultKeySize): CryptoResult[PrivateKey] =
   ## Generate random private key for scheme ``scheme``.
   ##
   ## ``bits`` is number of bits for RSA key, ``bits`` value must be in
-  ## [512, 4096], default value is 2048 bits.
+  ## [2048, 4096], default value is 3072 bits.
   case scheme
-  of RSA:
-    let rsakey = ? RsaPrivateKey.random(rng, bits).orError(KeyError)
-    ok(PrivateKey(scheme: scheme, rsakey: rsakey))
-  of Ed25519:
+  of PKScheme.RSA:
+    when supported(PKScheme.RSA):
+      let rsakey = ? RsaPrivateKey.random(rng, bits).orError(KeyError)
+      ok(PrivateKey(scheme: scheme, rsakey: rsakey))
+    else:
+      err(SchemeError)
+  of PKScheme.Ed25519:
+    when supported(PKScheme.Ed25519):
+      let edkey = EdPrivateKey.random(rng)
+      ok(PrivateKey(scheme: scheme, edkey: edkey))
+    else:
+      err(SchemeError)
+  of PKScheme.ECDSA:
+    when supported(PKScheme.ECDSA):
+      let eckey = ? ecnist.EcPrivateKey.random(Secp256r1, rng).orError(KeyError)
+      ok(PrivateKey(scheme: scheme, eckey: eckey))
+    else:
+      err(SchemeError)
+  of PKScheme.Secp256k1:
+    when supported(PKScheme.Secp256k1):
+      let skkey = SkPrivateKey.random(rng)
+      ok(PrivateKey(scheme: scheme, skkey: skkey))
+    else:
+      err(SchemeError)
+
+proc random*(T: typedesc[PrivateKey], rng: var BrHmacDrbgContext,
+             bits = RsaDefaultKeySize): CryptoResult[PrivateKey] =
+  ## Generate random private key using default public-key cryptography scheme.
+  ##
+  ## Default public-key cryptography schemes are following order:
+  ## ed25519, secp256k1, RSA, secp256r1.
+  ##
+  ## So will be used first available (supported) method.
+  when supported(PKScheme.Ed25519):
     let edkey = EdPrivateKey.random(rng)
-    ok(PrivateKey(scheme: scheme, edkey: edkey))
-  of ECDSA:
-    let eckey = ? ecnist.EcPrivateKey.random(Secp256r1, rng).orError(KeyError)
-    ok(PrivateKey(scheme: scheme, eckey: eckey))
-  of Secp256k1:
+    ok(PrivateKey(scheme: PKScheme.Ed25519, edkey: edkey))
+  elif supported(PKScheme.Secp256k1):
     let skkey = SkPrivateKey.random(rng)
-    ok(PrivateKey(scheme: scheme, skkey: skkey))
+    ok(PrivateKey(scheme: PKScheme.Secp256k1, skkey: skkey))
+  elif supported(PKScheme.RSA):
+    let rsakey = ? RsaPrivateKey.random(rng, bits).orError(KeyError)
+    ok(PrivateKey(scheme: PKScheme.RSA, rsakey: rsakey))
+  elif supported(PKScheme.ECDSA):
+    let eckey = ? ecnist.EcPrivateKey.random(Secp256r1, rng).orError(KeyError)
+    ok(PrivateKey(scheme: PKScheme.ECDSA, eckey: eckey))
   else:
     err(SchemeError)
 
-proc random*(
-    T: typedesc[KeyPair], scheme: PKScheme,
-    rng: var BrHmacDrbgContext, bits = DefaultKeySize): CryptoResult[KeyPair] =
+proc random*(T: typedesc[KeyPair], scheme: PKScheme,
+             rng: var BrHmacDrbgContext,
+             bits = RsaDefaultKeySize): CryptoResult[KeyPair] =
   ## Generate random key pair for scheme ``scheme``.
   ##
   ## ``bits`` is number of bits for RSA key, ``bits`` value must be in
   ## [512, 4096], default value is 2048 bits.
   case scheme
-  of RSA:
-    let pair = ? RsaKeyPair.random(rng, bits).orError(KeyError)
-    ok(KeyPair(
-      seckey: PrivateKey(scheme: scheme, rsakey: pair.seckey),
-      pubkey: PublicKey(scheme: scheme, rsakey: pair.pubkey)))
-  of Ed25519:
+  of PKScheme.RSA:
+    when supported(PKScheme.RSA):
+      let pair = ? RsaKeyPair.random(rng, bits).orError(KeyError)
+      ok(KeyPair(
+        seckey: PrivateKey(scheme: scheme, rsakey: pair.seckey),
+        pubkey: PublicKey(scheme: scheme, rsakey: pair.pubkey)))
+    else:
+      err(SchemeError)
+  of PKScheme.Ed25519:
+    when supported(PKScheme.Ed25519):
+      let pair = EdKeyPair.random(rng)
+      ok(KeyPair(
+        seckey: PrivateKey(scheme: scheme, edkey: pair.seckey),
+        pubkey: PublicKey(scheme: scheme, edkey: pair.pubkey)))
+    else:
+      err(SchemeError)
+  of PKScheme.ECDSA:
+    when supported(PKScheme.ECDSA):
+      let pair = ? EcKeyPair.random(Secp256r1, rng).orError(KeyError)
+      ok(KeyPair(
+        seckey: PrivateKey(scheme: scheme, eckey: pair.seckey),
+        pubkey: PublicKey(scheme: scheme, eckey: pair.pubkey)))
+    else:
+      err(SchemeError)
+  of PKScheme.Secp256k1:
+    when supported(PKScheme.Secp256k1):
+      let pair = SkKeyPair.random(rng)
+      ok(KeyPair(
+        seckey: PrivateKey(scheme: scheme, skkey: pair.seckey),
+        pubkey: PublicKey(scheme: scheme, skkey: pair.pubkey)))
+    else:
+      err(SchemeError)
+
+proc random*(T: typedesc[KeyPair], rng: var BrHmacDrbgContext,
+             bits = RsaDefaultKeySize): CryptoResult[KeyPair] =
+  ## Generate random private pair of keys using default public-key cryptography
+  ## scheme.
+  ##
+  ## Default public-key cryptography schemes are following order:
+  ## ed25519, secp256k1, RSA, secp256r1.
+  ##
+  ## So will be used first available (supported) method.
+  when supported(PKScheme.Ed25519):
     let pair = EdKeyPair.random(rng)
     ok(KeyPair(
-      seckey: PrivateKey(scheme: scheme, edkey: pair.seckey),
-      pubkey: PublicKey(scheme: scheme, edkey: pair.pubkey)))
-  of ECDSA:
-    let pair = ? EcKeyPair.random(Secp256r1, rng).orError(KeyError)
-    ok(KeyPair(
-      seckey: PrivateKey(scheme: scheme, eckey: pair.seckey),
-      pubkey: PublicKey(scheme: scheme, eckey: pair.pubkey)))
-  of Secp256k1:
+      seckey: PrivateKey(scheme: PKScheme.Ed25519, edkey: pair.seckey),
+      pubkey: PublicKey(scheme: PKScheme.Ed25519, edkey: pair.pubkey)))
+  elif supported(PKScheme.Secp256k1):
     let pair = SkKeyPair.random(rng)
     ok(KeyPair(
-      seckey: PrivateKey(scheme: scheme, skkey: pair.seckey),
-      pubkey: PublicKey(scheme: scheme, skkey: pair.pubkey)))
+      seckey: PrivateKey(scheme: PKScheme.Secp256k1, skkey: pair.seckey),
+      pubkey: PublicKey(scheme: PKScheme.Secp256k1, skkey: pair.pubkey)))
+  elif supported(PKScheme.RSA):
+    let pair = ? RsaKeyPair.random(rng, bits).orError(KeyError)
+    ok(KeyPair(
+      seckey: PrivateKey(scheme: PKScheme.RSA, rsakey: pair.seckey),
+      pubkey: PublicKey(scheme: PKScheme.RSA, rsakey: pair.pubkey)))
+  elif supported(PKScheme.ECDSA):
+    let pair = ? EcKeyPair.random(Secp256r1, rng).orError(KeyError)
+    ok(KeyPair(
+      seckey: PrivateKey(scheme: PKScheme.ECDSA, eckey: pair.seckey),
+      pubkey: PublicKey(scheme: PKScheme.ECDSA, eckey: pair.pubkey)))
   else:
     err(SchemeError)
 
 proc getKey*(key: PrivateKey): CryptoResult[PublicKey] =
   ## Get public key from corresponding private key ``key``.
   case key.scheme
-  of RSA:
-    let rsakey = key.rsakey.getKey()
-    ok(PublicKey(scheme: RSA, rsakey: rsakey))
-  of Ed25519:
-    let edkey = key.edkey.getKey()
-    ok(PublicKey(scheme: Ed25519, edkey: edkey))
-  of ECDSA:
-    let eckey = ? key.eckey.getKey().orError(KeyError)
-    ok(PublicKey(scheme: ECDSA, eckey: eckey))
-  of Secp256k1:
-    let skkey = key.skkey.getKey()
-    ok(PublicKey(scheme: Secp256k1, skkey: skkey))
-  else:
-    err(KeyError)
+  of PKScheme.RSA:
+    when supported(PKScheme.RSA):
+      let rsakey = key.rsakey.getKey()
+      ok(PublicKey(scheme: RSA, rsakey: rsakey))
+    else:
+      err(SchemeError)
+  of PKScheme.Ed25519:
+    when supported(PKScheme.Ed25519):
+      let edkey = key.edkey.getKey()
+      ok(PublicKey(scheme: Ed25519, edkey: edkey))
+    else:
+      err(SchemeError)
+  of PKScheme.ECDSA:
+    when supported(PKScheme.ECDSA):
+      let eckey = ? key.eckey.getKey().orError(KeyError)
+      ok(PublicKey(scheme: ECDSA, eckey: eckey))
+    else:
+      err(SchemeError)
+  of PKScheme.Secp256k1:
+    when supported(PKScheme.Secp256k1):
+      let skkey = key.skkey.getKey()
+      ok(PublicKey(scheme: Secp256k1, skkey: skkey))
+    else:
+      err(SchemeError)
 
 proc toRawBytes*(key: PrivateKey | PublicKey,
                  data: var openarray[byte]): CryptoResult[int] =
@@ -185,31 +335,51 @@ proc toRawBytes*(key: PrivateKey | PublicKey,
   ##
   ## Returns number of bytes (octets) needed to store private key ``key``.
   case key.scheme
-  of RSA:
-    key.rsakey.toBytes(data).orError(KeyError)
-  of Ed25519:
-    ok(key.edkey.toBytes(data))
-  of ECDSA:
-    key.eckey.toBytes(data).orError(KeyError)
-  of Secp256k1:
-    key.skkey.toBytes(data).orError(KeyError)
-  else:
-    err(KeyError)
+  of PKScheme.RSA:
+    when supported(PKScheme.RSA):
+      key.rsakey.toBytes(data).orError(KeyError)
+    else:
+      err(SchemeError)
+  of PKScheme.Ed25519:
+    when supported(PKScheme.Ed25519):
+      ok(key.edkey.toBytes(data))
+    else:
+      err(SchemeError)
+  of PKScheme.ECDSA:
+    when supported(PKScheme.ECDSA):
+      key.eckey.toBytes(data).orError(KeyError)
+    else:
+      err(SchemeError)
+  of PKScheme.Secp256k1:
+    when supported(PKScheme.Secp256k1):
+      key.skkey.toBytes(data).orError(KeyError)
+    else:
+      err(SchemeError)
 
 proc getRawBytes*(key: PrivateKey | PublicKey): CryptoResult[seq[byte]] =
   ## Return private key ``key`` in binary form (using scheme's own
   ## serialization).
   case key.scheme
-  of RSA:
-    key.rsakey.getBytes().orError(KeyError)
-  of Ed25519:
-    ok(key.edkey.getBytes())
-  of ECDSA:
-    key.eckey.getBytes().orError(KeyError)
-  of Secp256k1:
-    ok(key.skkey.getBytes())
-  else:
-    err(KeyError)
+  of PKScheme.RSA:
+    when supported(PKScheme.RSA):
+      key.rsakey.getBytes().orError(KeyError)
+    else:
+      err(SchemeError)
+  of PKScheme.Ed25519:
+    when supported(PKScheme.Ed25519):
+      ok(key.edkey.getBytes())
+    else:
+      err(SchemeError)
+  of PKScheme.ECDSA:
+    when supported(PKScheme.ECDSA):
+      key.eckey.getBytes().orError(KeyError)
+    else:
+      err(SchemeError)
+  of PKScheme.Secp256k1:
+    when supported(PKScheme.Secp256k1):
+      ok(key.skkey.getBytes())
+    else:
+      err(SchemeError)
 
 proc toBytes*(key: PrivateKey, data: var openarray[byte]): CryptoResult[int] =
   ## Serialize private key ``key`` (using libp2p protobuf scheme) and store
@@ -276,12 +446,18 @@ proc init*[T: PrivateKey|PublicKey](key: var T, data: openarray[byte]): bool =
   ## Returns ``true`` on success.
   var id: uint64
   var buffer: seq[byte]
-  if len(data) > 0:
+  if len(data) <= 0:
+    false
+  else:
     var pb = initProtoBuffer(@data)
     let r1 = pb.getField(1, id)
     let r2 = pb.getField(2, buffer)
-    if r1.isOk() and r1.get() and r2.isOk() and r2.get():
-      if cast[int8](id) in SupportedSchemesInt and len(buffer) > 0:
+    if not(r1.isOk() and r1.get() and r2.isOk() and r2.get()):
+      false
+    else:
+      if cast[int8](id) notin SupportedSchemesInt or len(buffer) <= 0:
+        false
+      else:
         var scheme = cast[PKScheme](cast[int8](id))
         when key is PrivateKey:
           var nkey = PrivateKey(scheme: scheme)
@@ -289,23 +465,41 @@ proc init*[T: PrivateKey|PublicKey](key: var T, data: openarray[byte]): bool =
           var nkey = PublicKey(scheme: scheme)
         case scheme:
         of PKScheme.RSA:
-          if init(nkey.rsakey, buffer).isOk:
-            key = nkey
-            return true
+          when supported(PKScheme.RSA):
+            if init(nkey.rsakey, buffer).isOk:
+              key = nkey
+              true
+            else:
+              false
+          else:
+            false
         of PKScheme.Ed25519:
-          if init(nkey.edkey, buffer):
-            key = nkey
-            return true
+          when supported(PKScheme.Ed25519):
+            if init(nkey.edkey, buffer):
+              key = nkey
+              true
+            else:
+              false
+          else:
+            false
         of PKScheme.ECDSA:
-          if init(nkey.eckey, buffer).isOk:
-            key = nkey
-            return true
+          when supported(PKScheme.ECDSA):
+            if init(nkey.eckey, buffer).isOk:
+              key = nkey
+              true
+            else:
+              false
+          else:
+            false
         of PKScheme.Secp256k1:
-          if init(nkey.skkey, buffer).isOk:
-            key = nkey
-            return true
-        else:
-          return false
+          when supported(PKScheme.Secp256k1):
+            if init(nkey.skkey, buffer).isOk:
+              key = nkey
+              true
+            else:
+              false
+          else:
+            false
 
 proc init*(sig: var Signature, data: openarray[byte]): bool =
   ## Initialize signature ``sig`` from raw binary form.
@@ -321,7 +515,7 @@ proc init*[T: PrivateKey|PublicKey](key: var T, data: string): bool =
   ##
   ## Returns ``true`` on success.
   try:
-    key.init(fromHex(data))
+    key.init(utils.fromHex(data))
   except ValueError:
     false
 
@@ -331,7 +525,7 @@ proc init*(sig: var Signature, data: string): bool =
   ##
   ## Returns ``true`` on success.
   try:
-    sig.init(fromHex(data))
+    sig.init(utils.fromHex(data))
   except ValueError:
     false
 
@@ -366,40 +560,46 @@ proc init*(t: typedesc[PrivateKey], data: string): CryptoResult[PrivateKey] =
   ## Create new private key from libp2p's protobuf serialized hexadecimal string
   ## form.
   try:
-    t.init(fromHex(data))
+    t.init(utils.fromHex(data))
   except ValueError:
     err(KeyError)
 
-proc init*(t: typedesc[PrivateKey], key: rsa.RsaPrivateKey): PrivateKey =
-  PrivateKey(scheme: RSA, rsakey: key)
-proc init*(t: typedesc[PrivateKey], key: EdPrivateKey): PrivateKey =
-  PrivateKey(scheme: Ed25519, edkey: key)
-proc init*(t: typedesc[PrivateKey], key: SkPrivateKey): PrivateKey =
-  PrivateKey(scheme: Secp256k1, skkey: key)
-proc init*(t: typedesc[PrivateKey], key: ecnist.EcPrivateKey): PrivateKey =
-  PrivateKey(scheme: ECDSA, eckey: key)
+when supported(PKScheme.RSA):
+  proc init*(t: typedesc[PrivateKey], key: rsa.RsaPrivateKey): PrivateKey =
+    PrivateKey(scheme: RSA, rsakey: key)
+  proc init*(t: typedesc[PublicKey], key: rsa.RsaPublicKey): PublicKey =
+    PublicKey(scheme: RSA, rsakey: key)
 
-proc init*(t: typedesc[PublicKey], key: rsa.RsaPublicKey): PublicKey =
-  PublicKey(scheme: RSA, rsakey: key)
-proc init*(t: typedesc[PublicKey], key: EdPublicKey): PublicKey =
-  PublicKey(scheme: Ed25519, edkey: key)
-proc init*(t: typedesc[PublicKey], key: SkPublicKey): PublicKey =
-  PublicKey(scheme: Secp256k1, skkey: key)
-proc init*(t: typedesc[PublicKey], key: ecnist.EcPublicKey): PublicKey =
-  PublicKey(scheme: ECDSA, eckey: key)
+when supported(PKScheme.Ed25519):
+  proc init*(t: typedesc[PrivateKey], key: EdPrivateKey): PrivateKey =
+    PrivateKey(scheme: Ed25519, edkey: key)
+  proc init*(t: typedesc[PublicKey], key: EdPublicKey): PublicKey =
+    PublicKey(scheme: Ed25519, edkey: key)
+
+when supported(PKScheme.Secp256k1):
+  proc init*(t: typedesc[PrivateKey], key: SkPrivateKey): PrivateKey =
+    PrivateKey(scheme: Secp256k1, skkey: key)
+  proc init*(t: typedesc[PublicKey], key: SkPublicKey): PublicKey =
+    PublicKey(scheme: Secp256k1, skkey: key)
+
+when supported(PKScheme.ECDSA):
+  proc init*(t: typedesc[PrivateKey], key: ecnist.EcPrivateKey): PrivateKey =
+    PrivateKey(scheme: ECDSA, eckey: key)
+  proc init*(t: typedesc[PublicKey], key: ecnist.EcPublicKey): PublicKey =
+    PublicKey(scheme: ECDSA, eckey: key)
 
 proc init*(t: typedesc[PublicKey], data: string): CryptoResult[PublicKey] =
   ## Create new public key from libp2p's protobuf serialized hexadecimal string
   ## form.
   try:
-    t.init(fromHex(data))
+    t.init(utils.fromHex(data))
   except ValueError:
     err(KeyError)
 
 proc init*(t: typedesc[Signature], data: string): CryptoResult[Signature] =
   ## Create new signature from serialized hexadecimal string form.
   try:
-    t.init(fromHex(data))
+    t.init(utils.fromHex(data))
   except ValueError:
     err(SigError)
 
@@ -409,15 +609,25 @@ proc `==`*(key1, key2: PublicKey): bool {.inline.} =
   if key1.scheme == key2.scheme:
     case key1.scheme
     of PKScheme.RSA:
-      (key1.rsakey == key2.rsakey)
+      when supported(PKScheme.RSA):
+        (key1.rsakey == key2.rsakey)
+      else:
+        false
     of PKScheme.Ed25519:
-      (key1.edkey == key2.edkey)
+      when supported(PKScheme.Ed25519):
+        (key1.edkey == key2.edkey)
+      else:
+        false
     of PKScheme.ECDSA:
-      (key1.eckey == key2.eckey)
+      when supported(PKScheme.ECDSA):
+        (key1.eckey == key2.eckey)
+      else:
+        false
     of PKScheme.Secp256k1:
-      (key1.skkey == key2.skkey)
-    of PKScheme.NoSupport:
-      false
+      when supported(PKScheme.Secp256k1):
+        (key1.skkey == key2.skkey)
+      else:
+        false
   else:
     false
 
@@ -427,15 +637,25 @@ proc `==`*(key1, key2: PrivateKey): bool =
   if key1.scheme == key2.scheme:
     case key1.scheme
     of PKScheme.RSA:
-      (key1.rsakey == key2.rsakey)
+      when supported(PKScheme.RSA):
+        (key1.rsakey == key2.rsakey)
+      else:
+        false
     of PKScheme.Ed25519:
-      (key1.edkey == key2.edkey)
+      when supported(PKScheme.Ed25519):
+        (key1.edkey == key2.edkey)
+      else:
+        false
     of PKScheme.ECDSA:
-      (key1.eckey == key2.eckey)
+      when supported(PKScheme.ECDSA):
+        (key1.eckey == key2.eckey)
+      else:
+        false
     of PKScheme.Secp256k1:
-      (key1.skkey == key2.skkey)
-    of PKScheme.NoSupport:
-      false
+      when supported(PKScheme.Secp256k1):
+        (key1.skkey == key2.skkey)
+      else:
+        false
   else:
     false
 
@@ -443,29 +663,49 @@ proc `$`*(key: PrivateKey|PublicKey): string =
   ## Get string representation of private/public key ``key``.
   case key.scheme:
   of PKScheme.RSA:
-    $(key.rsakey)
+    when supported(PKScheme.RSA):
+      $(key.rsakey)
+    else:
+      "unsupported RSA key"
   of PKScheme.Ed25519:
-    "ed25519 key (" & $key.edkey & ")"
+    when supported(PKScheme.Ed25519):
+      "ed25519 key (" & $key.edkey & ")"
+    else:
+      "unsupported ed25519 key"
   of PKScheme.ECDSA:
-    "secp256r1 key (" & $key.eckey & ")"
+    when supported(PKScheme.ECDSA):
+      "secp256r1 key (" & $key.eckey & ")"
+    else:
+      "unsupported secp256r1 key"
   of PKScheme.Secp256k1:
-    "secp256k1 key (" & $key.skkey & ")"
-  of PKScheme.NoSupport:
-    "not supported"
+    when supported(PKScheme.Secp256k1):
+      "secp256k1 key (" & $key.skkey & ")"
+    else:
+      "unsupported secp256k1 key"
 
 func shortLog*(key: PrivateKey|PublicKey): string =
   ## Get short string representation of private/public key ``key``.
   case key.scheme:
   of PKScheme.RSA:
-    ($key.rsakey).shortLog
+    when supported(PKScheme.RSA):
+      ($key.rsakey).shortLog
+    else:
+      "unsupported RSA key"
   of PKScheme.Ed25519:
-    "ed25519 key (" & ($key.edkey).shortLog & ")"
+    when supported(PKScheme.Ed25519):
+      "ed25519 key (" & ($key.edkey).shortLog & ")"
+    else:
+      "unsupported ed25519 key"
   of PKScheme.ECDSA:
-    "secp256r1 key (" & ($key.eckey).shortLog & ")"
+    when supported(PKScheme.ECDSA):
+      "secp256r1 key (" & ($key.eckey).shortLog & ")"
+    else:
+      "unsupported secp256r1 key"
   of PKScheme.Secp256k1:
-    "secp256k1 key (" & ($key.skkey).shortLog & ")"
-  of PKScheme.NoSupport:
-    "not supported"
+    when supported(PKScheme.Secp256k1):
+      "secp256k1 key (" & ($key.skkey).shortLog & ")"
+    else:
+      "unsupported secp256k1 key"
 
 proc `$`*(sig: Signature): string =
   ## Get string representation of signature ``sig``.
@@ -478,54 +718,74 @@ proc sign*(key: PrivateKey,
   var res: Signature
   case key.scheme:
   of PKScheme.RSA:
-    let sig = ? key.rsakey.sign(data).orError(SigError)
-    res.data = ? sig.getBytes().orError(SigError)
-    ok(res)
+    when supported(PKScheme.RSA):
+      let sig = ? key.rsakey.sign(data).orError(SigError)
+      res.data = ? sig.getBytes().orError(SigError)
+      ok(res)
+    else:
+      err(SchemeError)
   of PKScheme.Ed25519:
-    let sig = key.edkey.sign(data)
-    res.data = sig.getBytes()
-    ok(res)
+    when supported(PKScheme.Ed25519):
+      let sig = key.edkey.sign(data)
+      res.data = sig.getBytes()
+      ok(res)
+    else:
+      err(SchemeError)
   of PKScheme.ECDSA:
-    let sig = ? key.eckey.sign(data).orError(SigError)
-    res.data = ? sig.getBytes().orError(SigError)
-    ok(res)
+    when supported(PKScheme.ECDSA):
+      let sig = ? key.eckey.sign(data).orError(SigError)
+      res.data = ? sig.getBytes().orError(SigError)
+      ok(res)
+    else:
+      err(SchemeError)
   of PKScheme.Secp256k1:
-    let sig = key.skkey.sign(data)
-    res.data = sig.getBytes()
-    ok(res)
-  else:
-    err(SigError)
+    when supported(PKScheme.Secp256k1):
+      let sig = key.skkey.sign(data)
+      res.data = sig.getBytes()
+      ok(res)
+    else:
+      err(SchemeError)
 
 proc verify*(sig: Signature, message: openarray[byte], key: PublicKey): bool =
   ## Verify signature ``sig`` using message ``message`` and public key ``key``.
   ## Return ``true`` if message signature is valid.
   case key.scheme:
   of PKScheme.RSA:
-    var signature: RsaSignature
-    if signature.init(sig.data).isOk:
-      signature.verify(message, key.rsakey)
+    when supported(PKScheme.RSA):
+      var signature: RsaSignature
+      if signature.init(sig.data).isOk:
+        signature.verify(message, key.rsakey)
+      else:
+        false
     else:
       false
   of PKScheme.Ed25519:
-    var signature: EdSignature
-    if signature.init(sig.data):
-      signature.verify(message, key.edkey)
+    when supported(PKScheme.Ed25519):
+      var signature: EdSignature
+      if signature.init(sig.data):
+        signature.verify(message, key.edkey)
+      else:
+        false
     else:
       false
   of PKScheme.ECDSA:
-    var signature: EcSignature
-    if signature.init(sig.data).isOk:
-      signature.verify(message, key.eckey)
+    when supported(PKScheme.ECDSA):
+      var signature: EcSignature
+      if signature.init(sig.data).isOk:
+        signature.verify(message, key.eckey)
+      else:
+        false
     else:
       false
   of PKScheme.Secp256k1:
-    var signature: SkSignature
-    if signature.init(sig.data).isOk:
-      signature.verify(message, key.skkey)
+    when supported(PKScheme.Secp256k1):
+      var signature: SkSignature
+      if signature.init(sig.data).isOk:
+        signature.verify(message, key.skkey)
+      else:
+        false
     else:
       false
-  else:
-    false
 
 template makeSecret(buffer, hmactype, secret, seed: untyped) {.dirty.}=
   var ctx: hmactype
@@ -565,9 +825,6 @@ proc stretchKeys*(cipherType: string, hashType: string,
   elif cipherType == "TwofishCTR":
     result.ivsize = twofish256.sizeBlock
     result.keysize = twofish256.sizeKey
-  elif cipherType == "BLOWFISH":
-    result.ivsize = 8
-    result.keysize = 32
 
   var seed = "key expansion"
   result.macsize = 20
@@ -614,7 +871,7 @@ proc mac*(secret: Secret, id: int): seq[byte] {.inline.} =
 
 proc ephemeral*(
     scheme: ECDHEScheme,
-    rng: var BrHmacDrbgContext): CryptoResult[KeyPair] =
+    rng: var BrHmacDrbgContext): CryptoResult[EcKeyPair] =
   ## Generate ephemeral keys used to perform ECDHE.
   var keypair: EcKeyPair
   if scheme == Secp256r1:
@@ -623,12 +880,10 @@ proc ephemeral*(
     keypair = ? EcKeyPair.random(Secp384r1, rng).orError(KeyError)
   elif scheme == Secp521r1:
     keypair = ? EcKeyPair.random(Secp521r1, rng).orError(KeyError)
-  ok(KeyPair(
-    seckey: PrivateKey(scheme: ECDSA, eckey: keypair.seckey),
-    pubkey: PublicKey(scheme: ECDSA, eckey: keypair.pubkey)))
+  ok(EcKeyPair(keypair))
 
 proc ephemeral*(
-    scheme: string, rng: var BrHmacDrbgContext): CryptoResult[KeyPair] =
+    scheme: string, rng: var BrHmacDrbgContext): CryptoResult[EcKeyPair] =
   ## Generate ephemeral keys used to perform ECDHE using string encoding.
   ##
   ## Currently supported encoding strings are P-256, P-384, P-521, if encoding
@@ -642,33 +897,6 @@ proc ephemeral*(
   else:
     ephemeral(Secp521r1, rng)
 
-proc makeSecret*(remoteEPublic: PublicKey, localEPrivate: PrivateKey,
-                 data: var openarray[byte]): int =
-  ## Calculate shared secret using remote ephemeral public key
-  ## ``remoteEPublic`` and local ephemeral private key ``localEPrivate`` and
-  ## store shared secret to ``data``.
-  ##
-  ## Note this procedure supports only ECDSA keys.
-  ##
-  ## Returns number of bytes (octets) used to store shared secret data, or
-  ## ``0`` on error.
-  if remoteEPublic.scheme == ECDSA:
-    if localEPrivate.scheme == remoteEPublic.scheme:
-      result = toSecret(remoteEPublic.eckey, localEPrivate.eckey, data)
-
-proc getSecret*(remoteEPublic: PublicKey,
-                localEPrivate: PrivateKey): seq[byte] =
-  ## Calculate shared secret using remote ephemeral public key
-  ## ``remoteEPublic`` and local ephemeral private key ``localEPrivate`` and
-  ## store shared secret to ``data``.
-  ##
-  ## Note this procedure supports only ECDSA keys.
-  ##
-  ## Returns shared secret on success.
-  if remoteEPublic.scheme == ECDSA:
-    if localEPrivate.scheme == remoteEPublic.scheme:
-      result = getSecret(remoteEPublic.eckey, localEPrivate.eckey)
-
 proc getOrder*(remotePubkey, localNonce: openarray[byte],
                localPubkey, remoteNonce: openarray[byte]): CryptoResult[int] =
   ## Compare values and calculate `order` parameter.
@@ -707,14 +935,12 @@ proc selectBest*(order: int, p1, p2: string): string =
     s = strutils.split(p2, ",")
   else:
     var p = strutils.split(p1, ",")
-    result = p[0]
-    return
+    return p[0]
 
   for felement in f:
     for selement in s:
       if felement == selement:
-        result = felement
-        return
+        return felement
 
 proc createProposal*(nonce, pubkey: openarray[byte],
                      exchanges, ciphers, hashes: string): seq[byte] =
@@ -729,7 +955,7 @@ proc createProposal*(nonce, pubkey: openarray[byte],
   msg.write(4, ciphers)
   msg.write(5, hashes)
   msg.finish()
-  shallowCopy(result, msg.buffer)
+  msg.buffer
 
 proc decodeProposal*(message: seq[byte], nonce, pubkey: var seq[byte],
                      exchanges, ciphers, hashes: var string): bool =
@@ -757,7 +983,7 @@ proc createExchange*(epubkey, signature: openarray[byte]): seq[byte] =
   msg.write(1, epubkey)
   msg.write(2, signature)
   msg.finish()
-  shallowCopy(result, msg.buffer)
+  msg.buffer
 
 proc decodeExchange*(message: seq[byte],
                      pubkey, signature: var seq[byte]): bool =
diff --git a/libp2p/protocols/secure/secio.nim b/libp2p/protocols/secure/secio.nim
index bbd3950a2..4cd2e6bc5 100644
--- a/libp2p/protocols/secure/secio.nim
+++ b/libp2p/protocols/secure/secio.nim
@@ -280,7 +280,7 @@ method handshake*(s: Secio, conn: Connection, initiator: bool = false): Future[S
     remoteEBytesPubkey: seq[byte]
     remoteEBytesSig: seq[byte]
     remotePubkey: PublicKey
-    remoteEPubkey: PublicKey = PublicKey(scheme: ECDSA)
+    remoteEPubkey: ecnist.EcPublicKey
     remoteESignature: Signature
     remoteExchanges: string
     remoteCiphers: string
@@ -317,7 +317,8 @@ method handshake*(s: Secio, conn: Connection, initiator: bool = false): Future[S
     raise (ref SecioError)(msg: "Remote proposal decoding failed")
 
   if not remotePubkey.init(remoteBytesPubkey):
-    trace "Remote public key incorrect or corrupted", pubkey = remoteBytesPubkey.shortLog
+    trace "Remote public key incorrect or corrupted",
+          pubkey = remoteBytesPubkey.shortLog
     raise (ref SecioError)(msg: "Remote public key incorrect or corrupted")
 
   remotePeerId = PeerID.init(remotePubkey).tryGet()
@@ -342,7 +343,7 @@ method handshake*(s: Secio, conn: Connection, initiator: bool = false): Future[S
 
   var ekeypair = ephemeral(scheme, s.rng[]).tryGet()
   # We need EC public key in raw binary form
-  var epubkey = ekeypair.pubkey.eckey.getRawBytes().tryGet()
+  var epubkey = ekeypair.pubkey.getRawBytes().tryGet()
   var localCorpus = request[4..^1] & answer & epubkey
   var signature = s.localPrivateKey.sign(localCorpus).tryGet()
 
@@ -370,16 +371,14 @@ method handshake*(s: Secio, conn: Connection, initiator: bool = false): Future[S
 
   trace "Signature verified", scheme = remotePubkey.scheme
 
-  if not remoteEPubkey.eckey.initRaw(remoteEBytesPubkey):
+  if not remoteEPubkey.initRaw(remoteEBytesPubkey):
     trace "Remote ephemeral public key incorrect or corrupted",
           pubkey = toHex(remoteEBytesPubkey)
     raise (ref SecioError)(msg: "Remote ephemeral public key incorrect or corrupted")
 
   var secret = getSecret(remoteEPubkey, ekeypair.seckey)
   if len(secret) == 0:
-    trace "Shared secret could not be created",
-          pubkeyScheme = remoteEPubkey.scheme,
-          seckeyScheme = ekeypair.seckey.scheme
+    trace "Shared secret could not be created"
     raise (ref SecioError)(msg: "Shared secret could not be created")
 
   trace "Shared secret calculated", secret = secret.shortLog
diff --git a/libp2p/standard_setup.nim b/libp2p/standard_setup.nim
index 9ab8c262c..619c7d452 100644
--- a/libp2p/standard_setup.nim
+++ b/libp2p/standard_setup.nim
@@ -50,7 +50,7 @@ proc newStandardSwitch*(privKey = none(PrivateKey),
     raise (ref CatchableError)(msg: "Cannot initialize RNG")
 
   let
-    seckey = privKey.get(otherwise = PrivateKey.random(ECDSA, rng[]).tryGet())
+    seckey = privKey.get(otherwise = PrivateKey.random(rng[]).tryGet())
     peerInfo = PeerInfo.init(seckey, [address])
     mplexProvider = newMuxerProvider(createMplex, MplexCodec)
     transports = @[Transport(TcpTransport.init(transportFlags))]
diff --git a/tests/testpkifilter.nim b/tests/testpkifilter.nim
new file mode 100644
index 000000000..e87641213
--- /dev/null
+++ b/tests/testpkifilter.nim
@@ -0,0 +1,239 @@
+## Nim-Libp2p
+## Copyright (c) 2018 Status Research & Development GmbH
+## Licensed under either of
+##  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
+##  * MIT license ([LICENSE-MIT](LICENSE-MIT))
+## at your option.
+## This file may not be copied, modified, or distributed except according to
+## those terms.
+when defined(nimHasUsed): {.used.}
+
+import unittest
+import ../libp2p/crypto/crypto
+import nimcrypto/utils
+
+let rng = newRng()
+
+const ECDSA_PrivateKey = """
+  080312793077020101042070896381749FF6B30381C045F627C68C3062749BB53CB13
+  11FA07A7AEAB0A225A00A06082A8648CE3D030107A14403420004B17DAFF40C3221A5
+  0889A3FA9BB9DA4996AA1FE80D37358FBC6C88D89CD65738B4738C07CFD42F55293EB
+  3A56DB224EDCD36E51076F43A63203F8936D868EF18
+"""
+const ECDSA_PublicKey = """
+  0803125B3059301306072A8648CE3D020106082A8648CE3D03010703420004B17DAFF
+  40C3221A50889A3FA9BB9DA4996AA1FE80D37358FBC6C88D89CD65738B4738C07CFD4
+  2F55293EB3A56DB224EDCD36E51076F43A63203F8936D868EF18
+"""
+const SECP256k1_PrivateKey = """
+  080212209A0F994F5022D9D7B67ACEB26AA4D9F29B2628DBDCC28597469CB0049B6AB
+  348
+"""
+const SECP256k1_PublicKey = """
+  08021221039111FA29B374FE94B885408C45DF4647D09438C6E1F91F9B277A96CADD0
+  8A2B8
+"""
+const ED25519_PrivateKey = """
+  08011240E1BFE38E35F9669CE77F6BE1A551560896B59A3F510537205F3AC1EDAD421
+  601C9D5C25AA2FC61B950976D6E5EC26425F8D4BFFE17169A4DE5A246B7154CB2B5
+"""
+const ED25519_PublicKey = """
+  08011220C9D5C25AA2FC61B950976D6E5EC26425F8D4BFFE17169A4DE5A246B7154CB
+  2B5
+"""
+const RSA_PrivateKey = """
+  080012E80D308206E40201000282018100B5F2CABD05BE70474B262A2715B8C4FE74C
+  6F628757FADB3F4815881CD9F8D3D2583757DF178B9BDCB207EB183A260934E6580C9
+  3B75789ACADAC13C9DD5A21A6BEDC4845A76D32F61F37C69B2C0E9D1161459FB1C93C
+  E13E3EA0436B82086DF4EC95860D910D32B134610C20E84834A4B9A40C5B4D6FB0732
+  FF5332D8050221DA5101639044B6E2B18659E242FEEE58F4FF90BC9BEFF740E22C1A5
+  02774E4A0B103F750B829D6B1034908DB8338374EE2EF972A0E760DA9CC42F7D160CB
+  33C4918308389CD7EF98D58378BB8CF8F8314131C6654903C704EE6BC069B223A39DE
+  1CF1D5B0E34CE02522CFADF24AAF526445F7673CDE19F62C6D70266D1F7D03F98F9BD
+  69C1BC78662BB9F52D90C2D1841680A9E6528E52BF2F83B84EC73D819240029A677F5
+  AD8EF963843D36DB556B214E09A72B589FA139AFAED0EE5409AFFCAAEFC06329E2945
+  A727E1AED64C1935F17F6F1E8FDD1B4AE69CACC3DAD8153059B5775A0A3B0EF38E3A1
+  8CFE3DB4338F53F03B6CA30E729A5EC510C68CE662902030100010282018012759C7E
+  0AEC24460768CAD4064F25A54F41B44DAC8614A07249012AC22AD2D08652CD03C710E
+  17F50F16E09227AC1E3900B9A425046FDC26E9C3D08A256BF4880F4B18060113821D1
+  853B7519CE9AAA3CDC39B8D1506992F9078FFFE134639A9A4AB12DBA380BC48E0308C
+  63764D8511C547D07D1EE11AFCC4BBD2C266073B3ED8B5461BE8C4A25BBAF0EC576D8
+  9863EC0F55A6DD073E8595ACB5CAB60614FFFC95936CDC125A96C0E792FF7A53A4C0D
+  B2345A9DDA7BA81249912BD6A5D9355CD41A73B0E2A8D76ED7BB4D5B9AD98E5DD72CC
+  0C01D55CF89ADC4DE4D7457BFFC88F7DBE0E0C77725920DFF7B37B05E47BF7E930584
+  D8E3FD054189282EF5EF1882135FCEF02A709E4596C58D47B0A18AFD6C5ACE1C8074D
+  CEAE1693628623A98122D711DEF1D0BEC0E8FFD9D7BA3E3A0D9BF2E38FF240D255408
+  2D47E4D5120693CDF62D4C0A55BE170183FC6B363471FB04431BB0D4C00FD4A5B9D70
+  F26CDE6842A1895C6E166289FFA2BDC81DF4FC32DC1C4E95C5AE9064E841C7C8F5BDB
+  50281C100DE58C728695043A22FB9893CD659FDE3DFD9919BA70A758E2432E6043E35
+  49E7EF335D39D8A7DEF0FA9485B616C71758226E4003F6760E1A7975222E79C28BAD0
+  D550D5750D0CE2B07ED90672BE130AA161D527F1012CED2013F7556E1B03BA0335501
+  3EDA0B3AE086D0A7825CBEB229C61999446042CC732F59DCB5E2502DF439AED0E77C4
+  218994FE78FAC6BD5E72AEFFECB29C7854D8CA0D39D7E68D0E78806413D0033E6AD20
+  CFD36819EFFD53B7720BD3E938A1DEC9ADB4CF6CADD2BF7F0281C100D17CB4ED5777A
+  B4A5A609EC731643D6E981B8207BDB83803F1E1F6A6B51A3B79F0A25C77275C9840B7
+  4D91487E3FE91117CD0D9D68B13248A0656BFF616A22C57B18EBBE9F4AFE7DB1E5B38
+  07B23FBCDCC8215B196EBBED746109EDABF2F0359C82198D2C92145DE0598A2056333
+  52DBB59DBFF059E7C7754B99F9F0792FAB1519D3718D353498A460F468099E20075CF
+  08211CD7668DBA1A77D7BDACFC91EC380E28B4851F13F1BD826FABBED060CFE1291D1
+  7C1861EF137C85F26EEB79AE570281C100C56F2B9974BA72F40750C6CE20C054340E4
+  791861773B023017DB8C5B7BF75DADF8A4A93DD106364B3FD4226085FCD18D3A9F66A
+  0E6591EC6C415892D047B1E37E5D31B580EB88C6A909881A34DA876DE0A934E1E311F
+  058860725587A9B14B7121DBF3762426A8B88EAAA73958B3784E485429576AC9A0305
+  DED39F2650701DD742A5F9875AE1A0F154FB3CED9C48E2D5ACF8162736F53F9467940
+  7F566DAD0EC4CEDAFCA6661012BC9DB3C7CE0038077628D4F209C8BC9A5D752007CF1
+  105D0281C100C174F2F8C3EFC585B294CBCC943647ED1C173B2BBEEEA2FC31A2454F8
+  AABA105694DE72A3A756E3D458A2282D9E4576DEB96F7DDC7D2EBE6DA090F85160717
+  F95B46965EC1685640E9CA80CC43EBE51C16A2833A2F6FA21BD79E7DB4F11D8F70983
+  B3E905A219A0E0109058708275B7B7EEB2157EB0EFAC9BD7982B1AA9874DBD5AFC88B
+  68F91B85A1EBD3301E90E17BD8B7A58D22AE8F356821A0016026117CE6474FED078F4
+  C828048EF002151972A03281A570985576D9D6F6D85357C779D0281C01065CEABF166
+  FC360FB79BA436F2F6674BD641C0B502B1B071CD8D92BE582EE67FEB632306A2B94F4
+  FC31F2D29CC57C9C422DA1A567C413100921E6B12C9D61E307F1364A021BCF323F6E5
+  0833D565FA1E886FC05370F2AAFC61256B98CA6D68B7F89C5FE90C026B53CC6E53826
+  9FE3350723F6205D9B1B8A6E5BFBEADD7B543FD7F0269E9CCFD00FE888D7012F53828
+  E2DA931CBB692CAB71F5E14513451614A108F940DABFCD9BEAC4557EE503BD5196A21
+  522C61508521D7DB77A384BA696
+"""
+const RSA_PublicKey = """
+  080012A603308201A2300D06092A864886F70D01010105000382018F003082018A028
+  2018100B5F2CABD05BE70474B262A2715B8C4FE74C6F628757FADB3F4815881CD9F8D
+  3D2583757DF178B9BDCB207EB183A260934E6580C93B75789ACADAC13C9DD5A21A6BE
+  DC4845A76D32F61F37C69B2C0E9D1161459FB1C93CE13E3EA0436B82086DF4EC95860
+  D910D32B134610C20E84834A4B9A40C5B4D6FB0732FF5332D8050221DA5101639044B
+  6E2B18659E242FEEE58F4FF90BC9BEFF740E22C1A502774E4A0B103F750B829D6B103
+  4908DB8338374EE2EF972A0E760DA9CC42F7D160CB33C4918308389CD7EF98D58378B
+  B8CF8F8314131C6654903C704EE6BC069B223A39DE1CF1D5B0E34CE02522CFADF24AA
+  F526445F7673CDE19F62C6D70266D1F7D03F98F9BD69C1BC78662BB9F52D90C2D1841
+  680A9E6528E52BF2F83B84EC73D819240029A677F5AD8EF963843D36DB556B214E09A
+  72B589FA139AFAED0EE5409AFFCAAEFC06329E2945A727E1AED64C1935F17F6F1E8FD
+  D1B4AE69CACC3DAD8153059B5775A0A3B0EF38E3A18CFE3DB4338F53F03B6CA30E729
+  A5EC510C68CE66290203010001
+"""
+
+const
+  RSATestMessage = "RSA " & (
+    when supported(PKScheme.RSA): "(enabled)" else: "(disabled)") & " test"
+  EcdsaTestMessage = "ECDSA " & (
+    when supported(PKScheme.ECDSA): "(enabled)" else: "(disabled)") & " test"
+  EdTestMessage = "ED25519 " & (
+    when supported(PKScheme.Ed25519): "(enabled)" else: "(disabled)") & " test"
+  SecpTestMessage = "SECP256k1 " & (
+    when supported(PKScheme.Secp256k1): "(enabled)" else: "(disabled)") & " test"
+
+suite "Public key infrastructure filtering test suite":
+  test RSATestMessage:
+    when not(supported(PKScheme.RSA)):
+      let sk2048 = PrivateKey.random(PKScheme.RSA, rng[], 2048)
+      let sk3072 = PrivateKey.random(PKScheme.RSA, rng[], 3072)
+      let sk4096 = PrivateKey.random(PKScheme.RSA, rng[], 4096)
+      let kp2048 = KeyPair.random(PKScheme.RSA, rng[], 2048)
+      let kp3072 = KeyPair.random(PKScheme.RSA, rng[], 3072)
+      let kp4096 = KeyPair.random(PKScheme.RSA, rng[], 4096)
+      let sk = PrivateKey.init(fromHex(stripSpaces(RSA_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(RSA_PublicKey)))
+      check:
+        sk2048.isErr() == true
+        sk3072.isErr() == true
+        sk4096.isErr() == true
+        kp2048.isErr() == true
+        kp3072.isErr() == true
+        kp4096.isErr() == true
+        sk2048.error == CryptoError.SchemeError
+        sk3072.error == CryptoError.SchemeError
+        sk4096.error == CryptoError.SchemeError
+        kp2048.error == CryptoError.SchemeError
+        kp3072.error == CryptoError.SchemeError
+        kp4096.error == CryptoError.SchemeError
+        sk.isErr() == true
+        pk.isErr() == true
+        sk.error == CryptoError.KeyError
+        pk.error == CryptoError.KeyError
+    else:
+      let sk2048 = PrivateKey.random(PKScheme.RSA, rng[], 2048)
+      let kp2048 = KeyPair.random(PKScheme.RSA, rng[], 2048)
+      let sk = PrivateKey.init(fromHex(stripSpaces(RSA_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(RSA_PublicKey)))
+      check:
+        sk2048.isOk() == true
+        kp2048.isOk() == true
+        sk.isOk() == true
+        pk.isOk() == true
+
+  test EcdsaTestMessage:
+    when not(supported(PKScheme.ECDSA)):
+      let rsk = PrivateKey.random(PKScheme.ECDSA, rng[])
+      let rkp = KeyPair.random(PKScheme.ECDSA, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(ECDSA_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(ECDSA_PublicKey)))
+      check:
+        rsk.isErr() == true
+        rkp.isErr() == true
+        rsk.error == CryptoError.SchemeError
+        rkp.error == CryptoError.SchemeError
+        sk.isErr() == true
+        pk.isErr() == true
+        sk.error == CryptoError.KeyError
+        pk.error == CryptoError.KeyError
+    else:
+      let rsk = PrivateKey.random(PKScheme.ECDSA, rng[])
+      let rkp = KeyPair.random(PKScheme.ECDSA, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(ECDSA_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(ECDSA_PublicKey)))
+      check:
+        rsk.isOk() == true
+        rkp.isOk() == true
+        sk.isOk() == true
+        pk.isOk() == true
+
+  test EdTestMessage:
+    when not(supported(PKScheme.Ed25519)):
+      let rsk = PrivateKey.random(PKScheme.Ed25519, rng[])
+      let rkp = KeyPair.random(PKScheme.Ed25519, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(ED25519_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(ED25519_PublicKey)))
+      check:
+        rsk.isErr() == true
+        rkp.isErr() == true
+        rsk.error == CryptoError.SchemeError
+        rkp.error == CryptoError.SchemeError
+        sk.isErr() == true
+        pk.isErr() == true
+        sk.error == CryptoError.KeyError
+        pk.error == CryptoError.KeyError
+    else:
+      let rsk = PrivateKey.random(PKScheme.Ed25519, rng[])
+      let rkp = KeyPair.random(PKScheme.Ed25519, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(ED25519_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(ED25519_PublicKey)))
+      check:
+        rsk.isOk() == true
+        rkp.isOk() == true
+        sk.isOk() == true
+        pk.isOk() == true
+
+  test SecpTestMessage:
+    when not(supported(PKScheme.Secp256k1)):
+      let rsk = PrivateKey.random(PKScheme.Secp256k1, rng[])
+      let rkp = KeyPair.random(PKScheme.Secp256k1, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(SECP256k1_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(SECP256k1_PublicKey)))
+      check:
+        rsk.isErr() == true
+        rkp.isErr() == true
+        rsk.error == CryptoError.SchemeError
+        rkp.error == CryptoError.SchemeError
+        sk.isErr() == true
+        pk.isErr() == true
+        sk.error == CryptoError.KeyError
+        pk.error == CryptoError.KeyError
+    else:
+      let rsk = PrivateKey.random(PKScheme.Secp256k1, rng[])
+      let rkp = KeyPair.random(PKScheme.Secp256k1, rng[])
+      let sk = PrivateKey.init(fromHex(stripSpaces(SECP256k1_PrivateKey)))
+      let pk = PublicKey.init(fromHex(stripSpaces(SECP256k1_PublicKey)))
+      check:
+        rsk.isOk() == true
+        rkp.isOk() == true
+        sk.isOk() == true
+        pk.isOk() == true