Introduce BLS based keys

abc.nimble

@@ -1,4 +1,7 @@
 version = "0.1.0"
 author = "ABC Authors"
 description = "Asynchronous Blockchain"
-license = "MIT"
+license = "MIT"
+
+requires "https://github.com/markspanbroek/nim-blscurve#fix-nimble"
+requires "nimcrypto"

abc/keys.nim

@@ -0,0 +1,22 @@
+import pkg/blscurve as bls
+import pkg/nimcrypto
+
+type
+  PrivateKey* = distinct bls.SecretKey
+  PublicKey* = distinct bls.PublicKey
+
+proc `==`*(a, b: PrivateKey): bool {.borrow.}
+proc `==`*(a, b: PublicKey): bool {.borrow.}
+
+proc random*(_: type PrivateKey): PrivateKey =
+  var seed = newSeq[byte](64)
+  doAssert randomBytes(seed) == seed.len
+  doAssert deriveMasterSecretKey(bls.SecretKey(result), seed)
+  burnArray(seed)
+
+proc erase*(key: var PrivateKey) =
+  burnMem(key)
+
+proc toPublicKey*(private: PrivateKey): PublicKey =
+  doAssert publicFromSecret(bls.PublicKey(result), bls.SecretKey(private))
+

tests/nim.cfg

@@ -0,0 +1 @@
+--path:".."

tests/testKeys.nim

@@ -0,0 +1,20 @@
+import std/unittest
+import abc/keys
+
+suite "Keys":
+
+  test "generates random private keys":
+    check PrivateKey.random != PrivateKey.random
+
+  test "erases memory associated with a private key":
+    var key = PrivateKey.random
+    let bytes = cast[ptr[uint64]](addr key)
+    check bytes[] != 0
+    erase key
+    check bytes[] == 0
+
+  test "derives public key from private key":
+    let key1, key2 = PrivateKey.random()
+    check key1.toPublicKey == key1.toPublicKey
+    check key2.toPublicKey == key2.toPublicKey
+    check key1.toPublicKey != key2.toPublicKey