crypto: Implement ECSignatureCreatorImpl for OpenSSL

crypto/ec_signature_creator_openssl.cc

Index: crypto/ec_signature_creator_openssl.cc
diff --git a/crypto/ec_signature_creator_openssl.cc b/crypto/ec_signature_creator_openssl.cc
index 8854f5ed464de9c8fa1f658e1ca31b646cbbdea7..4898aa596d459befae31e21a1180ef088665df4c 100644
--- a/crypto/ec_signature_creator_openssl.cc
+++ b/crypto/ec_signature_creator_openssl.cc
@@ -4,13 +4,21 @@
 
 #include "crypto/ec_signature_creator_impl.h"
 
+#include <openssl/bn.h>
+#include <openssl/ec.h>
+#include <openssl/ecdsa.h>
+#include <openssl/evp.h>
+#include <openssl/sha.h>
+
 #include "base/logging.h"
+#include "crypto/ec_private_key.h"
+#include "crypto/openssl_util.h"
 
 namespace crypto {
 
 ECSignatureCreatorImpl::ECSignatureCreatorImpl(ECPrivateKey* key)
-    : key_(key) {
-  NOTIMPLEMENTED();
+    : key_(key), signature_len_(0) {
+  EnsureOpenSSLInit();
 }
 
 ECSignatureCreatorImpl::~ECSignatureCreatorImpl() {}
@@ -18,14 +26,59 @@ ECSignatureCreatorImpl::~ECSignatureCreatorImpl() {}
 bool ECSignatureCreatorImpl::Sign(const uint8* data,
                                   int data_len,
                                   std::vector<uint8>* signature) {
-  NOTIMPLEMENTED();
-  return false;
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  ScopedOpenSSL<EVP_MD_CTX, EVP_MD_CTX_destroy> ctx(EVP_MD_CTX_create());
+  size_t sig_len = 0;
+  if (!ctx.get() ||
+      !EVP_DigestSignInit(ctx.get(), NULL, EVP_sha256(), NULL, key_->key()) ||
+      !EVP_DigestSignUpdate(ctx.get(), data, data_len) ||
+      !EVP_DigestSignFinal(ctx.get(), NULL, &sig_len)) {
+    return false;
+  }
+
+  signature->resize(sig_len);
+  if (!EVP_DigestSignFinal(ctx.get(), &signature->front(), &sig_len))
+    return false;
+
+  // NOTE: A call to EVP_DigestSignFinal() with a NULL second parameter returns
+  // a maximum allocation size, while the call without a NULL returns the real
+  // one, which may be smaller.
+  signature->resize(sig_len);
+  return true;
 }
 
 bool ECSignatureCreatorImpl::DecodeSignature(const std::vector<uint8>& der_sig,
                                              std::vector<uint8>* out_raw_sig) {
-  NOTIMPLEMENTED();
-  return false;
+  OpenSSLErrStackTracer err_tracer(FROM_HERE);
+  // Create ECDSA_SIG object from DER-encoded data.
+  const unsigned char* der_data = der_sig.front();
+  ScopedOpenSSL<ECDSA_SIG, ECDSA_SIG_free> ecdsa_sig(
+      d2i_ECDSA_SIG(NULL, &der_data, static_cast<long>(der_sig.size())));
+  if (!ecdsa_sig.get())
+    return false;
+
+  // The result is made of two 32-byte vectors.
+  const size_t kMaxBytesPerBN = 32;

[wtc, 2013/10/17 20:51:11]

Starting with kMaxBitsPerBN will be useful when we use an elliptic curve whose
size is not a multiple of 8 bits, for example, P-521. For now, let's go for
simplicity.

+  std::vector<uint8> result;
+  result.resize(2 * kMaxBytesPerBN);
+  memset(&result[0], 0, result.size());
+
+  BIGNUM* r = ecdsa_sig.get()->r;
+  BIGNUM* s = ecdsa_sig.get()->s;
+  int r_bytes = BN_num_bytes(r);
+  int s_bytes = BN_num_bytes(s);
+  // NOTE: Can't really check for equality here since sometimes the value
+  // returned by BN_num_bytes() will be slightly smaller than kMaxBytesPerBN.
+  if (r_bytes > static_cast<int>(kMaxBytesPerBN) ||
+      s_bytes > static_cast<int>(kMaxBytesPerBN)) {
+    DLOG(ERROR) << "Invalid key sizes r(" << r_bytes << ") s(" << s_bytes
+                << ")";
+    return false;
+  }
+  BN_bn2bin(ecdsa_sig.get()->r, &result[kMaxBytesPerBN - r_bytes]);
+  BN_bn2bin(ecdsa_sig.get()->s, &result[2 * kMaxBytesPerBN - s_bytes]);
+  out_raw_sig->swap(result);
+  return true;
 }
 
 }  // namespace crypto