crypto: add an ed25519 digital signature module (#13476)

vlib/crypto/ed25519/examples/example.v

@@ -0,0 +1,41 @@
+module main
+
+import encoding.hex
+import encoding.base64
+import crypto.ed25519
+
+// adapted from https://asecuritysite.com/signatures/ed25519
+fn main() {
+	msg := 'Hello Girl'
+
+	publ, priv := ed25519.generate_key() or { panic(err.msg) }
+
+	m := msg.bytes()
+
+	sig := ed25519.sign(priv, m) or { panic(err.msg) }
+
+	println('=== Message ===')
+	println('Msg: $msg \nHash: $m')
+
+	println('=== Public key ===')
+	println('Public key (Hex): ${hex.encode(publ)}')
+	println('   Public key (Base64): ${base64.encode(publ)}')
+
+	println('=== Private key ===')
+	println('Private key: $priv.seed().hex()') // priv[0:32]
+	println('   Private key (Base64): ${base64.encode(priv.seed())}') // priv[0:32]
+	println('   Private key (Base64) Full key:  ${base64.encode(priv)}')
+	println('   Private key (Full key in Hex): ${hex.encode(priv)}')
+
+	println('=== signature (R,s) ===')
+	println('signature: R=${sig[0..32].hex()} s=${sig[32..64].hex()}')
+	println('   signature (Base64)=${base64.encode(sig)}')
+
+	rtn := ed25519.verify(publ, m, sig) or { panic(err.msg) }
+
+	if rtn {
+		println('Signature verified :$rtn')
+	} else {
+		println('signature does not verify :${!rtn}')
+	}
+}