Enhance the SM2Crypto signature and verification features, supporting ASN.1 DER format.

Author: numbcoder

lib/sm2_crypto.rb

@@ -101,9 +101,10 @@ def get_public_key(private_key)
   # @param private_key [String] private key, format: binary string
   # @param data [String]
   # @param sm3_hash [Boolean], option to sign with sm3 hash, default: false
-  # @param user_id [String], format: hex string, default: "31323334353637383132333435363738"
+  # @param user_id [String], format: hex string, default: "31323334353637383132333435363738" which is equal to utf-8 str "1234567812345678"
+  # @param asn1 [Boolean], option to return asn.1 der format signature, default: false
   # @return [String] signature, format: hex string
-  def sign(private_key, data, sm3_hash: false, user_id: "31323334353637383132333435363738")
+  def sign(private_key, data, sm3_hash: false, user_id: "31323334353637383132333435363738", asn1: false)
     data = data.unpack1("a*") unless data.ascii_only?
     if sm3_hash
       public_key = get_public_key(private_key)
@@ -130,7 +131,11 @@ def sign(private_key, data, sm3_hash: false, user_id: "3132333435363738313233343
       s = ((one + da).mod_inverse(n) * (k - (r * da))).to_i % n.to_i
     end
 
-    r.to_s(16).rjust(64, "0") + s.to_s(16).rjust(64, "0")
+    if asn1
+      OpenSSL::ASN1::Sequence.new([OpenSSL::ASN1::Integer.new(r), OpenSSL::ASN1::Integer.new(s)]).to_der.unpack1("H*")
+    else
+      r.to_s(16).rjust(64, "0") + s.to_s(16).rjust(64, "0")
+    end
   end
 
   # verify the signature with public_key
@@ -140,17 +145,28 @@ def sign(private_key, data, sm3_hash: false, user_id: "3132333435363738313233343
   # @param signature [String], hex string
   # @param sm3_hash [Boolean], option to sign with sm3 hash, default: false
   # @param user_id [String], format: hex string, default: "31323334353637383132333435363738"
+  # @param asn1 [Boolean], option to verify asn.1 der format signature, default: false
   # @return [Boolean] verify result
-  def verify(public_key, data, signature, sm3_hash: false, user_id: "31323334353637383132333435363738")
-    return false if signature.size != 128
+  def verify(public_key, data, signature, sm3_hash: false, user_id: "31323334353637383132333435363738", asn1: false)
+    if asn1
+      # return false if signature.size < 138
+
+      # parse asn1 der format hex string signature
+      der_seq = OpenSSL::ASN1.decode([signature].pack("H*"))
+      r = der_seq.value[0].value
+      s = der_seq.value[1].value
+    else
+      return false if signature.size != 128
+
+      r = OpenSSL::BN.new(signature[0, 64], 16)
+      s = OpenSSL::BN.new(signature[64, 64], 16)
+    end
 
     public_key = "\x04#{public_key}" if public_key.size == 64 && public_key[0] != "\x04"
     data = data.unpack1("a*") unless data.ascii_only?
     if sm3_hash
       data = OpenSSL::Digest.digest("SM3", za(public_key, user_id) + data)
     end
-    r = OpenSSL::BN.new(signature[0, 64], 16)
-    s = OpenSSL::BN.new(signature[64, 64], 16)
     n = OpenSSL::BN.new("FFFFFFFEFFFFFFFFFFFFFFFFFFFFFFFF7203DF6B21C6052B53BBF40939D54123", 16)
     e = OpenSSL::BN.new(data, 2)
 

test/test_sm2_crypto.rb

@@ -95,4 +95,30 @@ def test_sign_and_verify_with_hash
     sign2 = SM2Crypto.sign(SM2_PRIVATE_KEY, cjk_msg, sm3_hash: true)
     assert_equal true, SM2Crypto.verify(SM2_PUBLIC_KEY, cjk_msg, sign2, sm3_hash: true)
   end
+
+  def test_sign_and_verify_with_asn1
+    30.times do
+      msg = SecureRandom.alphanumeric(rand(1..100))
+      sign = SM2Crypto.sign(SM2_PRIVATE_KEY, msg, asn1: true)
+      verified = SM2Crypto.verify(SM2_PUBLIC_KEY, msg, sign, asn1: true)
+      unless verified
+        puts "msg: #{msg}"
+        puts "sign: #{sign}"
+      end
+      assert_equal true, verified
+    end
+  end
+
+  def test_sign_and_verify_with_asn1_and_hash
+    msg = "z0I15DTbsWjF"
+    signs = %w[
+      304402203bd708d89b9728af3939f77df68bd4c2bc3038cb5de92bfdfd11468165caa87302204136f5345177d1eb663e33c18922fed5440dec0cc68b3c39def76b87ef77d177
+      3045022100e84b35c282ec4afbf337fff6e978c99fd3126745f436f8abd3cc897b0c784d160220482aecc68fe47334385ac98af508ea589b11d0d22d4ac065d663bd1034eafd38
+      3045022100f10f4403dc670ceb30ae7b15c9ea06f01274fc8c796060ea39ae3d0eab37e310022049eef876e073d0595c6444cc3b23917948da706755a6a38a1f23e3841c67a279
+      3046022100f9762c583bef7331a7a16295d98c3413fa4fd7e579ace06842956ca9ce385752022100819eac8da0b92c5babacad868f3fe7af118bf1cbbc59c2629f54e8db925c7e4e
+    ]
+    signs.each do |sign|
+      assert_equal true, SM2Crypto.verify(SM2_PUBLIC_KEY, msg, sign, sm3_hash: true, asn1: true)
+    end
+  end
 end