/// <summary>
/// Loads a <see cref="ProtectedPrivateKey"/> from a JSON, according to Ethereum's
/// <a href="https://github.com/ethereum/wiki/wiki/Web3-Secret-Storage-Definition">Web3
/// Secret Storage Definition</a>.
/// </summary>
/// <param name="json">A JSON string that encodes a <see cref="ProtectedPrivateKey"/>.
/// </param>
/// <returns>A protected private key loaded from the given <paramref name="json"/>.
/// </returns>
/// <exception cref="JsonException">Thrown when the given <paramref name="json"/> is not
/// a valid JSON.</exception>
/// <exception cref="InvalidKeyJsonException">Thrown when the given key data lacks some
/// required fields or consists of wrong types.</exception>
/// <exception cref="UnsupportedKeyJsonException">Thrown when the given key data depends on
/// an unsupported features (e.g., KDF).</exception>
public static ProtectedPrivateKey FromJson(string json)
{
var options = new JsonDocumentOptions
{
AllowTrailingCommas = true,
CommentHandling = JsonCommentHandling.Skip,
};
using JsonDocument doc = JsonDocument.Parse(json, options);
JsonElement rootElement = doc.RootElement;
if (rootElement.ValueKind != JsonValueKind.Object)
{
throw new InvalidKeyJsonException(
"The root of the key JSON must be an object, but it is a/an " +
$"{rootElement.ValueKind}."
);
}
if (!rootElement.TryGetProperty("version", out JsonElement versionElement))
{
throw new InvalidKeyJsonException(
"The key JSON must contain \"version\" field, but it lacks."
);
}
if (versionElement.ValueKind != JsonValueKind.Number ||
!versionElement.TryGetDecimal(out decimal versionNum))
{
throw new InvalidKeyJsonException("The \"version\" field must be a number.");
}
else if (versionNum != 3)
{
throw new UnsupportedKeyJsonException(
$"The key JSON format version {versionNum} is unsupported; " +
"Only version 3 is supported."
);
}
string GetStringProperty(JsonElement element, string fieldName)
{
if (!element.TryGetProperty(fieldName, out JsonElement fieldElement))
{
throw new InvalidKeyJsonException(
$"The key JSON must contain \"{fieldName}\" field, but it lacks."
);
}
string str;
try
{
str = fieldElement.GetString();
}
catch (InvalidOperationException)
{
throw new InvalidKeyJsonException(
$"The \"{fieldName}\" field must be a string."
);
}
if (str is null)
{
throw new InvalidKeyJsonException(
$"The \"{fieldName}\" field must not be null, but a string."
);
}
return(str);
}
JsonElement GetObjectProperty(JsonElement element, string fieldName)
{
if (!element.TryGetProperty(fieldName, out var fieldElement))
{
throw new InvalidKeyJsonException(
$"The key JSON must contain \"{fieldName}\" field, but it lacks."
);
}
else if (fieldElement.ValueKind != JsonValueKind.Object)
{
throw new InvalidKeyJsonException(
$"The \"{fieldName}\" field must be an object, but it is a/an " +
$"{fieldElement.ValueKind}."
);
}
return(fieldElement);
}
byte[] GetHexProperty(JsonElement element, string fieldName)
{
string str = GetStringProperty(element, fieldName);
byte[] bytes;
try
{
bytes = ByteUtil.ParseHex(str);
}
catch (Exception e)
{
throw new InvalidKeyJsonException(
$"The \"{fieldName}\" field must be a hexadecimal string.\n{e}"
);
}
return(bytes);
}
JsonElement crypto = GetObjectProperty(rootElement, "crypto");
string cipherType = GetStringProperty(crypto, "cipher");
JsonElement cipherParamsElement = GetObjectProperty(crypto, "cipherparams");
byte[] ciphertext = GetHexProperty(crypto, "ciphertext");
byte[] mac = GetHexProperty(crypto, "mac");
string kdfType = GetStringProperty(crypto, "kdf");
JsonElement kdfParamsElement = GetObjectProperty(crypto, "kdfparams");
byte[] addressBytes = GetHexProperty(rootElement, "address");
Address address;
try
{
address = new Address(addressBytes);
}
catch (ArgumentException e)
{
throw new InvalidKeyJsonException(
"The \"address\" field must contain an Ethereum-style address which " +
"consists of 40 hexadecimal letters: " + e
);
}
var cipher = cipherType switch
{
"aes-128-ctr" => Aes128Ctr.FromJson(cipherParamsElement),
_ =>
throw new UnsupportedKeyJsonException(
$"Unsupported cipher type: \"{cipherType}\".")
};
IKdf kdf;
try
{
kdf = kdfType switch
{
"pbkdf2" => Pbkdf2.FromJson(kdfParamsElement),
"scrypt" => Scrypt.FromJson(kdfParamsElement),
_ =>
throw new UnsupportedKeyJsonException(
$"Unsupported cipher type: \"{kdfType}\".")
};
}
catch (ArgumentException e)
{
throw new InvalidKeyJsonException(e.Message);
}
return(new ProtectedPrivateKey(address, kdf, mac, cipher, ciphertext));
}
public void FromJson()
{
var options = new JsonDocumentOptions
{
AllowTrailingCommas = true,
CommentHandling = JsonCommentHandling.Skip,
};
Pbkdf2 <Sha256Digest> Load(string json)
{
using (JsonDocument doc = JsonDocument.Parse(json, options))
{
return((Pbkdf2 <Sha256Digest>)Pbkdf2.FromJson(doc.RootElement));
}
}
var kdf = Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
");
Assert.Equal(10240, kdf.Iterations);
Assert.Equal(32, kdf.KeyLength);
TestUtils.AssertBytesEqual(
new byte[]
{
0x3e, 0xea, 0xaf, 0x35, 0xda, 0x70, 0x92, 0x83, 0x87, 0xca, 0xe1,
0xea, 0xd3, 0x1e, 0xd7, 0x82, 0xb1, 0x13, 0x5d, 0x75, 0x78, 0xa8,
0x9d, 0x95, 0xe3, 0x0c, 0xc9, 0x14, 0x01, 0x0b, 0xa2, 0xed,
}.ToImmutableArray(),
kdf.Salt
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
// ""c"": 10240, // lacks
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": true, // not a number
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": null, // not a number, but null
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
// ""dklen"": 32, // lacks
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": false, // not a number
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": null, // not a number, but null
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
// ""prf"": ""hmac-sha256"", // lacks
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": 123, // not a string, but a number
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <UnsupportedKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha512"", // unsupported prf
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2ed"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha256"",
// ""salt"": ""..."", // lacks
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": 1234, // not a string, but a number
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""not a hexadecimal string"",
}
")
);
Assert.Throws <InvalidKeyJsonException>(() =>
Load(@"
{
""c"": 10240,
""dklen"": 32,
""prf"": ""hmac-sha256"",
""salt"": ""3eeaaf35da70928387cae1ead31ed782b1135d7578a89d95e30cc914010ba2e"",
// salt: invalid length
}
")
);
}