[webcrypto] Implement Sign() and Verify() for RSA-SSA using OpenSSL.

content/child/webcrypto/openssl/rsa_ssa_openssl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/child/webcrypto/crypto_data.h"
 #include "content/child/webcrypto/openssl/key_openssl.h"
 #include "content/child/webcrypto/openssl/rsa_key_openssl.h"
+#include "content/child/webcrypto/openssl/util_openssl.h"
 #include "content/child/webcrypto/status.h"
+#include "crypto/openssl_util.h"
+#include "crypto/scoped_openssl_types.h"
 #include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"
 
 namespace content {
 
 namespace webcrypto {
 
 namespace {
 
+// Extracts the OpenSSL key and digest from a WebCrypto key. The returned
+// pointers will remain valid as long as |key| is alive.
+Status GetPKeyAndDigest(const blink::WebCryptoKey& key,
+                        EVP_PKEY** pkey,
+                        const EVP_MD** digest) {
+  *pkey = AsymKeyOpenSsl::Cast(key)->key();
+
+  *digest = GetDigest(key.algorithm().rsaHashedParams()->hash().id());
+  if (!*digest)
+    return Status::ErrorUnsupported();
+
+  return Status::Success();
+}
+
 class RsaSsaImplementation : public RsaHashedAlgorithm {
  public:
   RsaSsaImplementation()
       : RsaHashedAlgorithm(blink::WebCryptoKeyUsageVerify,
                            blink::WebCryptoKeyUsageSign) {}
 
-  // TODO(eroman): Implement Sign() and Verify().
+  virtual Status Sign(const blink::WebCryptoAlgorithm& algorithm,
+                      const blink::WebCryptoKey& key,
+                      const CryptoData& data,
+                      std::vector<uint8_t>* buffer) const OVERRIDE {
+    if (key.type() != blink::WebCryptoKeyTypePrivate)
+      return Status::ErrorUnexpectedKeyType();
+
+    crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+    crypto::ScopedEVP_MD_CTX ctx(EVP_MD_CTX_create());
+
+    EVP_PKEY* private_key = NULL;
+    const EVP_MD* digest = NULL;
+    Status status = GetPKeyAndDigest(key, &private_key, &digest);
+    if (status.IsError())
+      return status;
+
+    // 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.
+    size_t sig_len = 0;
+    if (!ctx.get() ||
+        !EVP_DigestSignInit(ctx.get(), NULL, digest, NULL, private_key) ||
+        !EVP_DigestSignUpdate(ctx.get(), data.bytes(), data.byte_length()) ||
+        !EVP_DigestSignFinal(ctx.get(), NULL, &sig_len)) {
+      return Status::OperationError();
+    }
+
+    buffer->resize(sig_len);
+    if (!EVP_DigestSignFinal(ctx.get(), &buffer->front(), &sig_len))
+      return Status::OperationError();
+
+    buffer->resize(sig_len);
+    return Status::Success();
+  }
+
+  virtual Status Verify(const blink::WebCryptoAlgorithm& algorithm,
+                        const blink::WebCryptoKey& key,
+                        const CryptoData& signature,
+                        const CryptoData& data,
+                        bool* signature_match) const OVERRIDE {
+    if (key.type() != blink::WebCryptoKeyTypePublic)
+      return Status::ErrorUnexpectedKeyType();
+
+    crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+    crypto::ScopedEVP_MD_CTX ctx(EVP_MD_CTX_create());
+
+    EVP_PKEY* public_key = NULL;
+    const EVP_MD* digest = NULL;
+    Status status = GetPKeyAndDigest(key, &public_key, &digest);
+    if (status.IsError())
+      return status;
+
+    if (1 != EVP_DigestVerifyInit(ctx.get(), NULL, digest, NULL, public_key))
+      return Status::OperationError();
+
+    if (1 !=
+        EVP_DigestVerifyUpdate(ctx.get(), data.bytes(), data.byte_length())) {
+      return Status::OperationError();
+    }
+
+    // This function takes a non-const pointer to the signature, however does
+    // not mutate it, so casting is safe.
+    // Also note that the return value can be:
+    //   1 --> Success
+    //   0 --> Verification failed
+    //  <0 --> Operation error
+    int rv = EVP_DigestVerifyFinal(ctx.get(),
+                                   const_cast<uint8_t*>(signature.bytes()),
+                                   signature.byte_length());
+    *signature_match = rv == 1;
+    return rv >= 0 ? Status::Success() : Status::OperationError();
+  }
 };
 
 }  // namespace
 
 AlgorithmImplementation* CreatePlatformRsaSsaImplementation() {
   return new RsaSsaImplementation;
 }
 
 }  // namespace webcrypto
 
 }  // namespace content