[webcrypto] Add error messages for failed operations.

content/renderer/webcrypto/webcrypto_util.h

Index: content/renderer/webcrypto/webcrypto_util.h
diff --git a/content/renderer/webcrypto/webcrypto_util.h b/content/renderer/webcrypto/webcrypto_util.h
index e3ea94b865ecce0d1dd84aa6c67265059fcad7b4..e1abe17856384e55e830748fb1eb8644f957d184 100644
--- a/content/renderer/webcrypto/webcrypto_util.h
+++ b/content/renderer/webcrypto/webcrypto_util.h
@@ -17,6 +17,164 @@ namespace content {
 
 namespace webcrypto {
 
+// Status indicates whether an operation completed successfully, or with an
+// error. The error is used for verification in unit-tests, as well as for
+// display to the user.
+//
+// As such, it is important that errors DO NOT reveal any sensitive material
+// (like key bytes).
+//
+// Care must be taken with what errors are reported back to blink when doing
+// compound operations like unwrapping a JWK key. In this case, errors
+// generated by the JWK import are not appropriate to report since the wrapped
+// JWK is not visible to the caller.
+class CONTENT_EXPORT Status {
+ public:
+  // Returns true if the Status represents an error (any one of them).
+  bool IsError() const;
+
+  // Returns true if the Status represent success.
+  bool IsSuccess() const;
+
+  // Returns a UTF-8 error message (non-localized) describing the error. This
+  // message is intended to be displayed in the dev tools console.
+  std::string ToString() const;
+
+  // Constructs a status representing success.
+  static Status Success();
+
+  // Constructs a status representing a generic error. It contains no extra
+  // details.
+  static Status Error();
+
+  // ------------------------------------
+  // Errors when importing a JWK formatted key
+  // ------------------------------------
+
+  // The key bytes could not parsed as JSON dictionary. This either
+  // means there was a parsing error, or the JSON object was not
+  // convertable to a dictionary.
+  static Status ErrorJwkNotDictionary();
+
+  // The required "kty" parameter was missing, or is not a string.
+  static Status ErrorJwkMissingKty();
+
+  // The "extractable" parameter was specified and was a boolean, but was
+  // incompatible with the value requested by the Web Crypto call.
+  static Status ErrorJwkExtractableInconsistent();
+
+  // The "alg" parameter could not be converted to an equivalent
+  // WebCryptoAlgorithm. Either it was malformed or unrecognized.
+  static Status ErrorJwkUnrecognizedAlgorithm();
+
+  // The "alg" parameter is incompatible with the (optional) Algorithm
+  // specified by the Web Crypto import operation.
+  static Status ErrorJwkAlgorithmInconsistent();
+
+  // The "alg" parameter was not provided, however neither was an algorithm
+  // provided by the Web Crypto import operation.
+  static Status ErrorJwkAlgorithmMissing();
+
+  // The "use" parameter was specified, however it couldn't be converted to an
+  // equivalent Web Crypto usage.
+  static Status ErrorJwkUnrecognizedUsage();
+
+  // The "use" parameter was specified, however it is incompatible with that
+  // specified by the Web Crypto import operation.
+  static Status ErrorJwkUsageInconsistent();
+
+  // The "k" parameter was either missing, could not be parsed as a base-64
+  // encoded string, or the decoded bytes were empty.
+  static Status ErrorJwkDecodeK();
+
+  // The "n" parameter was either missing, could not be parsed as a base-64
+  // encoded string, or the decoded bytes were empty.
+  static Status ErrorJwkDecodeN();
+
+  // The "e" parameter was either missing, could not be parsed as a base-64
+  // encoded string, or the decoded bytes were empty.
+  static Status ErrorJwkDecodeE();
+
+  // TODO(eroman): Private key import through JWK is not yet supported.
+  static Status ErrorJwkRsaPrivateKeyUnsupported();
+
+  // The "kty" parameter was given and was a string, however it was
+  // unrecognized.
+  static Status ErrorJwkUnrecognizedKty();
+
+  // ------------------------------------
+  // Other errors
+  // ------------------------------------
+
+  // No key data was provided when importing an spki, pkcs8, or jwk formatted
+  // key. This does not apply to raw format, since it is possible to have empty
+  // key data there.
+  static Status ErrorImportEmptyKeyData();
+
+  // The wrong key was used for the operation. For instance, a public key was
+  // used to verify a RsaSsaPkcs1v1_5 signature, or tried exporting a private
+  // key using spki format.
+  static Status ErrorUnexpectedKeyType();
+
+  // When doing an AES-CBC encryption/decryption, the "iv" parameter was not 16
+  // bytes.
+  static Status ErrorIncorrectSizeAesCbcIv();
+
+  // The data provided to an encrypt/decrypt/sign/verify operation was too
+  // large. This can either represent an internal limitation (for instance
+  // representing buffer lengths as uints), or an algorithm restriction (for
+  // instance RSAES can operation on messages relative to the length of the
+  // key's modulus).
+  static Status ErrorDataTooLarge();
+
+  // Something was unsupported or unimplemented. This can mean the algorithm in
+  // question was unsupported, some parameter combination was unsupported, or
+  // something has not yet been implemented.
+  static Status ErrorUnsupported();
+
+  // Something unexpected happened in the code, which implies there is a
+  // source-level bug. These should not happen, but safer to fail than simply
+  // DCHECK.
+  static Status ErrorUnexpected();
+
+  // The authentication tag length specified for AES-GCM encrypt/decrypt was
+  // either greater than 128 bits, or it was not a multiple of 8 bits.
+  // (zero length is allowed).
+  static Status ErrorInvalidAesGcmTagLength();
+
+  // The "publicExponent" used to generate a key was invalid: either no bytes
+  // were specified, or the number was too large to fit into an "unsigned long"
+  // (implemention limitation), or the exponent was zero.
+  static Status ErrorGenerateKeyPublicExponent();
+
+  // The algorithm was null when importing a raw-formatted key. In this case it
+  // is required.
+  static Status ErrorMissingAlgorithmImportRawKey();
+
+  // The modulus bytes were empty when importing an RSA public key.
+  static Status ErrorImportRsaEmptyModulus();
+
+  // The the modulus length was zero bits when generating an RSA public key.
+  static Status ErrorGenerateRsaZeroModulus();
+
+  // The exponent bytes were empty when importing an RSA public key.
+  static Status ErrorImportRsaEmptyExponent();
+
+  // An unextractable key was used by an operation which exports the key data.
+  static Status ErrorKeyNotExtractable();
+
+  // The key length specified when generating a key was invalid. Either it was
+  // zero, or it was not a multiple of 8 bits.
+  static Status ErrorGenerateKeyLength();
+
+ private:
+  // |error_details_utf8| can be NULL to indicate there was no error.
+  // Otherwise it is a UTF-8 string literal (the pointer must remain valid).
+  explicit Status(const char* error_details_utf8);
+
+  const char* error_details_;
+};
+
 // Returns a pointer to the start of |data|, or NULL if it is empty. This is a
 // convenience function for getting the pointer, and should not be used beyond
 // the expected lifetime of |data|.