/// <summary>
/// Generate encryption parameters.
/// </summary>
/// <exception cref="EncryptionException"/>
public static FieldLevelEncryptionParams Generate(FieldLevelEncryptionConfig config)
{
// Generate a random IV
var ivBytes = GenerateIv();
var ivValue = EncodingUtils.EncodeBytes(ivBytes, config.ValueEncoding);
// Generate an AES secret key
var secretKeyBytes = GenerateSecretKey();
// Encrypt the secret key
var encryptedSecretKeyBytes = RsaEncryption.WrapSecretKey(config.EncryptionCertificate.GetRSAPublicKey(), secretKeyBytes, config.OaepPaddingDigestAlgorithm);
var encryptedKeyValue = EncodingUtils.EncodeBytes(encryptedSecretKeyBytes, config.ValueEncoding);
// Compute the OAEP padding digest algorithm
var oaepPaddingDigestAlgorithmValue = config.OaepPaddingDigestAlgorithm.Replace("-", string.Empty);
return(new FieldLevelEncryptionParams
{
IvValue = ivValue,
EncryptedKeyValue = encryptedKeyValue,
OaepPaddingDigestAlgorithmValue = oaepPaddingDigestAlgorithmValue,
Config = config,
SecretKeyBytes = secretKeyBytes,
IvBytes = ivBytes
});
}
private void ComputeEncryptionCertificateFingerprintWhenNeeded()
{
try
{
if (_encryptionCertificate == null || !string.IsNullOrEmpty(_encryptionCertificateFingerprint))
{
// No encryption certificate set or certificate fingerprint already provided
return;
}
var certificateFingerprintBytes = Sha256Digest(_encryptionCertificate.RawData);
_encryptionCertificateFingerprint = EncodingUtils.EncodeBytes(certificateFingerprintBytes, FieldValueEncoding.Hex);
}
catch (Exception e)
{
throw new EncryptionException("Failed to compute encryption certificate fingerprint!", e);
}
}
private static JToken EncryptPayloadPath(JToken payloadToken, string jsonPathIn, string jsonPathOut,
FieldLevelEncryptionConfig config, FieldLevelEncryptionParams parameters)
{
if (payloadToken == null)
{
throw new ArgumentNullException(nameof(payloadToken));
}
if (jsonPathIn == null)
{
throw new ArgumentNullException(nameof(jsonPathIn));
}
if (jsonPathOut == null)
{
throw new ArgumentNullException(nameof(jsonPathOut));
}
var inJsonToken = payloadToken.SelectToken(jsonPathIn);
if (inJsonToken == null)
{
// Nothing to encrypt
return(payloadToken);
}
if (parameters == null)
{
// Generate encryption params
parameters = FieldLevelEncryptionParams.Generate(config);
}
// Encrypt data at the given JSON path
var inJsonString = JsonUtils.SanitizeJson(inJsonToken.ToString());
var inJsonBytes = Encoding.ASCII.GetBytes(inJsonString);
var encryptedValueBytes = EncryptBytes(parameters.GetSecretKeyBytes(), parameters.GetIvBytes(), inJsonBytes);
var encryptedValue = EncodingUtils.EncodeBytes(encryptedValueBytes, config.ValueEncoding);
// Delete data in clear
if (!"$".Equals(jsonPathIn))
{
inJsonToken.Parent.Remove();
}
else
{
// We need a JObject (we can't work with a JArray for instance)
payloadToken = JObject.Parse("{}");
}
// Add encrypted data and encryption fields at the given JSON path
JsonUtils.CheckOrCreateOutObject(payloadToken, jsonPathOut);
var outJsonToken = payloadToken.SelectToken(jsonPathOut) as JObject;
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.EncryptedValueFieldName, encryptedValue);
if (!string.IsNullOrEmpty(config.IvFieldName))
{
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.IvFieldName, parameters.IvValue);
}
if (!string.IsNullOrEmpty(config.EncryptedKeyFieldName))
{
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.EncryptedKeyFieldName, parameters.EncryptedKeyValue);
}
if (!string.IsNullOrEmpty(config.EncryptionCertificateFingerprintFieldName))
{
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.EncryptionCertificateFingerprintFieldName, config.EncryptionCertificateFingerprint);
}
if (!string.IsNullOrEmpty(config.EncryptionKeyFingerprintFieldName))
{
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.EncryptionKeyFingerprintFieldName, config.EncryptionKeyFingerprint);
}
if (!string.IsNullOrEmpty(config.OaepPaddingDigestAlgorithmFieldName))
{
JsonUtils.AddOrReplaceJsonKey(outJsonToken, config.OaepPaddingDigestAlgorithmFieldName, parameters.OaepPaddingDigestAlgorithmValue);
}
return(payloadToken);
}
