add fast_aggregate_verify

constantine/blssig_pop_on_bls12381_g2.nim

@@ -85,6 +85,7 @@ type
     cttBLS_PointNotInSubgroup
     cttBLS_ZeroSecretKey
     cttBLS_SecretKeyLargerThanCurveOrder
+    cttBLS_ZeroLengthAggregation
 
 # Comparisons
 # ------------------------------------------------------------------------------------------------
@@ -404,3 +405,39 @@ func verify*[T: byte|char](public_key: PublicKey, message: openarray[T], signatu
   if verified:
     return cttBLS_Success
   return cttBLS_VerificationFailure
+
+func fast_aggregate_verify*[T: byte|char](public_keys: openArray[PublicKey], message: openarray[T], signature: Signature): CttBLSStatus =
+  ## Check that a signature is valid for a message
+  ## under the aggregate of provided public keys.
+  ## returns `true` if the signature is valid, `false` otherwise.
+  ## 
+  ## For message domain separation purpose, the tag is `BLS_SIG_BLS12381G2_XMD:SHA-256_SSWU_RO_POP_`
+  ## 
+  ## Input:
+  ## - Public keys initialized by one of the key derivation or deserialization procedure.
+  ##   Or validated via validate_pubkey
+  ## - A message
+  ## - A signature initialized by one of the key derivation or deserialization procedure.
+  ##   Or validated via validate_pubkey
+  ## 
+  ## In particular, the public keys and signature are assumed to be on curve subgroup checked.
+
+  if public_keys.len == 0:
+    # IETF spec precondition
+    return cttBLS_ZeroLengthAggregation
+
+  # Deal with cases were pubkey or signature were mistakenly zero-init, due to a generic aggregation tentative for example
+  if signature.raw.isInf().bool:
+    return cttBLS_PointAtInfinity
+
+  for i in 0 ..< public_keys.len:
+    if public_keys[i].raw.isInf().bool:
+      return cttBLS_PointAtInfinity
+  
+  let verified = fastAggregateVerify(
+    toOpenArray(cast[ptr UncheckedArray[typeof public_keys[0].raw]](public_keys[0].raw.unsafeAddr), public_keys.low, public_keys.high),
+    message, signature.raw,
+    sha256, 128, augmentation = "", DST)
+  if verified:
+    return cttBLS_Success
+  return cttBLS_VerificationFailure

constantine/signatures/bls_signatures.nim

@@ -8,6 +8,7 @@
 
 import
     ../math/[ec_shortweierstrass, pairings],
+    ../math/elliptic/ec_shortweierstrass_batch_ops,
     ../math/constants/zoo_generators,
     ../hash_to_curve/hash_to_curve,
     ../hashes
@@ -94,7 +95,7 @@ func coreSign*[B1, B2, B3: byte|char, Sig, SecKey](
   signature.affine(sig)
 
 func coreVerify*[B1, B2, B3: byte|char, Pubkey, Sig](
-    pubKey: Pubkey,
+    pubkey: Pubkey,
     message: openarray[B1],
     signature: Sig,
     H: type CryptoHash,
@@ -119,8 +120,45 @@ func coreVerify*[B1, B2, B3: byte|char, Pubkey, Sig](
 
   # e(PK, H(msg))*e(sig, -G) == 1
   when Sig.G == G2:
-    pairing(gt, [pubKey, negG], [Q, signature])
+    pairing(gt, [pubkey, negG], [Q, signature])
   else:
-    pairing(gt, [Q, signature], [pubKey, negG])
+    pairing(gt, [Q, signature], [pubkey, negG])
 
   return gt.isOne().bool()
+
+# ############################################################
+#
+#                   Aggregate verification
+#
+# ############################################################
+#
+# Terminology:
+#
+# - fastAggregateVerify:
+#   Verify the aggregate of multiple signatures by multiple pubkeys
+#   on the same message.
+#
+# - aggregateVerify:
+#   Verify the aggregate of multiple signatures by multiple (pubkey, message) pairs
+#
+# - batchVerify:
+#   Verify that all (pubkey, message, signature) triplets are valid
+
+func fastAggregateVerify*[B1, B2, B3: byte|char, Pubkey, Sig](
+    pubkeys: openArray[Pubkey],
+    message: openarray[B1],
+    signature: Sig,
+    H: type CryptoHash,
+    k: static int,
+    augmentation: openarray[B2],
+    domainSepTag: openarray[B3]): bool =
+  ## Verify the aggregate of multiple signatures by multiple pubkeys
+  ## on the same message.
+  
+  var accum {.noinit.}: ECP_ShortW_Jac[Pubkey.F, Pubkey.G]
+  accum.sum_batch_vartime(pubkeys)
+
+  var aggPubkey {.noinit.}: Pubkey
+  aggPubkey.affine(accum)
+
+  aggPubkey.coreVerify(message, signature, H, k, augmentation, domainSepTag)

tests/t_blssig_pop_on_bls12381_g2.nim

@@ -13,13 +13,16 @@ import
   ../constantine/math/io/io_bigints
 
 type
+  # https://github.com/ethereum/bls12-381-tests/blob/master/formats/
+
   PubkeyField = object
     pubkey: array[48, byte]
-  SignatureField =object
-    signature: array[96, byte]
   DeserG1_test = object
     input: PubkeyField
     output: bool
+
+  SignatureField =object
+    signature: array[96, byte]
   DeserG2_test = object
     input: SignatureField
     output: bool
@@ -27,7 +30,6 @@ type
   InputSign = object
     privkey: array[32, byte]
     message: array[32, byte]
-
   Sign_test = object
     input: InputSign
     output: array[96, byte]
@@ -36,11 +38,18 @@ type
     pubkey: array[48, byte]
     message: array[32, byte]
     signature: array[96, byte]
-
   Verify_test = object
     input: InputVerify
     output: bool
 
+  InputFastAggregateVerify = object
+    pubkeys: seq[array[48, byte]]
+    message: array[32, byte]
+    signature: array[96, byte]
+  FastAggregateVerify_test = object
+    input: InputFastAggregateVerify
+    output: bool
+
 proc parseHook*[N: static int](src: string, pos: var int, value: var array[N, byte]) =
   var str: string
   parseHook(src, pos, str)
@@ -73,7 +82,7 @@ template testGen*(name, testData, TestType, body: untyped): untyped =
     var count = 0 # Need to fail if walkDir doesn't return anything
     var skipped = 0
     for dir, file in walkTests(astToStr(name), skipped):
-      stdout.write("       " & astToStr(name) & " test: " & alignLeft(file, 60))
+      stdout.write("       " & astToStr(name) & " test: " & alignLeft(file, 70))
       let testFile = readFile(dir/file)
       let testData = testFile.fromJson(TestType)
 
@@ -169,7 +178,7 @@ testGen(verify, testVector, Verify_test):
   var
     pubkey{.noInit.}: PublicKey
     signature{.noInit.}: Signature
-    status = cttBLS_Success
+    status = cttBLS_VerificationFailure
 
   block testChecks:
     status = pubkey.deserialize_public_key_compressed(testVector.input.pubkey)
@@ -181,8 +190,8 @@ testGen(verify, testVector, Verify_test):
       # For point at infinity, we want to make sure that "verify" itself handles them.
       break testChecks
 
-
     status = pubkey.verify(testVector.input.message, signature)
+  
   let success = status == cttBLS_Success
   doAssert success == testVector.output, block:
     "\Verification differs from expected \n" &
@@ -202,6 +211,32 @@ testGen(verify, testVector, Verify_test):
       doAssert s == cttBLS_Success
       doAssert output == testVector.input.signature
 
+testGen(fast_aggregate_verify, testVector, FastAggregateVerify_test):
+  var
+    pubkeys = newSeq[PublicKey](testVector.input.pubkeys.len)
+    signature{.noInit.}: Signature
+    status = cttBLS_VerificationFailure
+
+  block testChecks:
+    for i in 0 ..< testVector.input.pubkeys.len:
+      status = pubkeys[i].deserialize_public_key_compressed(testVector.input.pubkeys[i])
+      if status notin {cttBLS_Success, cttBLS_PointAtInfinity}:
+        # For point at infinity, we want to make sure that "verify" itself handles them.
+        break testChecks
+    
+    status = signature.deserialize_signature_compressed(testVector.input.signature)
+    if status notin {cttBLS_Success, cttBLS_PointAtInfinity}:
+      # For point at infinity, we want to make sure that "verify" itself handles them.
+      break testChecks
+
+    status = pubkeys.fast_aggregate_verify(testVector.input.message, signature)
+  
+  let success = status == cttBLS_Success
+  doAssert success == testVector.output, block:
+    "\Verification differs from expected \n" &
+    "   valid sig? " & $success & " (" & $status & ")\n" &
+    "   expected: " & $testVector.output
+
 suite "BLS signature on BLS12381G3 - ETH 2.0 test vectors":
   test "Deserialization_G1(PublicKey) -> bool":
     test_deserialization_G1()
@@ -211,3 +246,5 @@ suite "BLS signature on BLS12381G3 - ETH 2.0 test vectors":
     test_sign()
   test "verify(PublicKey, message, Signature) -> bool":
     test_verify()
+  test "fast_aggregate_verify(seq[PublicKey], message, Signature) -> bool":
+    test_fast_aggregate_verify()