Ecc Go Reference Documentation

Ecc

Current Version: 10.0.0

Elliptical Curve Cryptography class for generating ECDSA keys, computing shared secrets, and creating and verifying ECDSA signatures. Supports the following curves:

  • secp256r1 (also known as P-256 and prime256v1)
  • secp384r1 (also known as P-384)
  • secp521r1 (also known as P-521)
  • secp256k1 (This is the curve used for Bitcoin)
  • secp192r1
  • secp224r1
  • brainpoolP160r1
  • brainpoolP192r1
  • brainpoolP192r1
  • brainpoolP224r1
  • brainpoolP256r1
  • brainpoolP320r1
  • brainpoolP384r1
  • brainpoolP512r1

Additional curves will be supported in the future.

Object Creation

ec := chilkat.NewEcc()
...
ec.DisposeEcc()

Properties

AsnFormat
func (ec *Ecc) AsnFormat() bool
func (ec *Ecc) SetAsnFormat(b bool)
Introduced in version 9.5.0.97

If true, the ECDSA signatures produced by this object will use ASN.1 format. Otherwise the ECDSA signature will be a concatenation of the two raw byte arrays for r and s.

ECDSA signatures have two equal sized parts, r and s. There are two common formats for encoding the signature:

(a) Concatenating the raw byte array of r and s
(b) Encoding both into a structured ASN.1 / DER sequence.

The default value of this property is true, which is to use ASN.1, which is the behavior of earlier versions of Chilkat before this property was added.

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DebugLogFilePath
func (ec *Ecc) DebugLogFilePath() string
func (ec *Ecc) SetDebugLogFilePath(s string)

If set to a file path, causes each Chilkat method or property call to automatically append it's LastErrorText to the specified log file. The information is appended such that if a hang or crash occurs, it is possible to see the context in which the problem occurred, as well as a history of all Chilkat calls up to the point of the problem. The VerboseLogging property can be set to provide more detailed information.

This property is typically used for debugging the rare cases where a Chilkat method call hangs or generates an exception that halts program execution (i.e. crashes). A hang or crash should generally never happen. The typical causes of a hang are:

  1. a timeout related property was set to 0 to explicitly indicate that an infinite timeout is desired,
  2. the hang is actually a hang within an event callback (i.e. it is a hang within the application code), or
  3. there is an internal problem (bug) in the Chilkat code that causes the hang.

More Information and Examples
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LastErrorHtml
func (ec *Ecc) LastErrorHtml() string

Provides information in HTML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorText
func (ec *Ecc) LastErrorText() string

Provides information in plain-text format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastErrorXml
func (ec *Ecc) LastErrorXml() string

Provides information in XML format about the last method/property called. If a method call returns a value indicating failure, or behaves unexpectedly, examine this property to get more information.

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LastMethodSuccess
func (ec *Ecc) LastMethodSuccess() bool
func (ec *Ecc) SetLastMethodSuccess(b bool)

Indicate whether the last method call succeeded or failed. A value of true indicates success, a value of false indicates failure. This property is automatically set for method calls. It is not modified by property accesses. The property is automatically set to indicate success for the following types of method calls:

  • Any method that returns a string.
  • Any method returning a Chilkat object, binary bytes, or a date/time.
  • Any method returning a standard boolean status value where success = true and failure = false.
  • Any method returning an integer where failure is defined by a return value less than zero.

Note: Methods that do not fit the above requirements will always set this property equal to true. For example, a method that returns no value (such as a "void" in C++) will technically always succeed.

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VerboseLogging
func (ec *Ecc) VerboseLogging() bool
func (ec *Ecc) SetVerboseLogging(b bool)

If set to true, then the contents of LastErrorText (or LastErrorXml, or LastErrorHtml) may contain more verbose information. The default value is false. Verbose logging should only be used for debugging. The potentially large quantity of logged information may adversely affect peformance.

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Version
func (ec *Ecc) Version() string

Version of the component/library, such as "9.5.0.94"

More Information and Examples
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Methods

GenEccKey
func (ec *Ecc) GenEccKey(curveName string, prng *Prng) *PrivateKey
Introduced in version 9.5.0.52

Generates an ECDSA private key. The curveName specifies the curve name which determines the key size. The prng provides a source for generating the random private key.

The following curve names are accepted:

  • secp256r1 (also known as P-256 and prime256v1)
  • secp384r1 (also known as P-384)
  • secp521r1 (also known as P-521)
  • secp256k1 (This is the curve used for Bitcoin)
  • secp192r1
  • secp224r1
  • brainpoolP160r1
  • brainpoolP192r1
  • brainpoolP192r1
  • brainpoolP224r1
  • brainpoolP256r1
  • brainpoolP320r1
  • brainpoolP384r1
  • brainpoolP512r1

Returns nil on failure

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GenEccKey2
func (ec *Ecc) GenEccKey2(curveName string, encodedK string, encoding string) *PrivateKey
Introduced in version 9.5.0.55

Generates an ECDSA private key using a specified value for K. The curveName specifies the curve name which determines the key size. The encodedK is the encoded value of the private key. The encoding is the encoding used for encodedK, which can be "hex", "base64", "decimal", etc.

Note: This method is typically used for testing -- such as when the same private key is desired to produce results identical from run to run.

The following curve names are accepted:

  • secp256r1 (also known as P-256 and prime256v1)
  • secp384r1 (also known as P-384)
  • secp521r1 (also known as P-521)
  • secp256k1 (This is the curve used for Bitcoin)
  • secp192r1
  • secp224r1
  • brainpoolP160r1
  • brainpoolP192r1
  • brainpoolP192r1
  • brainpoolP224r1
  • brainpoolP256r1
  • brainpoolP320r1
  • brainpoolP384r1
  • brainpoolP512r1

Returns nil on failure

More Information and Examples
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SharedSecretENC
func (ec *Ecc) SharedSecretENC(privKey *PrivateKey, pubKey *PublicKey, encoding string) *string
Introduced in version 9.5.0.52

Computes a shared secret given a private and public key. For example, Alice and Bob can compute the identical shared secret by doing the following: Alice sends Bob her public key, and Bob calls SharedSecretENC with his private key and Alice's public key. Bob sends Alice his public key, and Alice calls SharedSecretENC with her private key and Bob's public key. Both calls to SharedSecretENC will produce the same result. The resulting bytes are returned in encoded string form (hex, base64, etc) as specified by encoding.

Note: The private and public keys must both be keys on the same ECDSA curve.

Returns nil on failure

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SignBd
func (ec *Ecc) SignBd(bdData *BinData, hashAlg string, encoding string, privKey *PrivateKey, prng *Prng) *string
Introduced in version 9.5.0.85

This method is the same as SignHashENC, except the actual data to be signed and the name of the hash algorithm is passed in. The following hash algorithms are supported: sha256, sha384, and sha512.

Returns nil on failure

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SignBdUsingCert
func (ec *Ecc) SignBdUsingCert(bdData *BinData, hashAlg string, encoding string, cert *Cert) *string
Introduced in version 9.5.0.91

Same as SignBd, but instead uses the private key of a certificate (assuming the cert's private key is ECDSA).

Returns nil on failure

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SignHashENC
func (ec *Ecc) SignHashENC(encodedHash string, encoding string, privkey *PrivateKey, prng *Prng) *string
Introduced in version 9.5.0.52

Computes an ECDSA signature on a hash. ECDSA signatures are computed and verified on the hashes of data (such as SHA1, SHA256, etc.). The hash of the data is passed in encodedHash. The encoding, such as "base64", "hex", etc. is passed in encoding. The ECDSA private key is passed in the 3rd argument (privkey). Given that creating an ECDSA signature involves the generation of random numbers, a PRNG is passed in the 4th argument (prng). The signature is returned as an encoded string using the encoding specified by the encoding argument.

Returns nil on failure

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VerifyBd
func (ec *Ecc) VerifyBd(bdData *BinData, hashAlg string, encodedSig string, encoding string, pubkey *PublicKey) int
Introduced in version 9.5.0.85

This method is the same as VerifyHashENC, except the actual data to be verified and the name of the hash algorithm is passed in. The following hash algorithms are supported: sha256, sha384, and sha512.

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VerifyHashENC
func (ec *Ecc) VerifyHashENC(encodedHash string, encodedSig string, encoding string, pubkey *PublicKey) int
Introduced in version 9.5.0.52

Verifies an ECDSA signature. ECDSA signatures are computed and verified on the hashes of data (such as SHA1, SHA256, etc.). The hash of the data is passed in encodedHash. The encoded signature is passed in encodedSig. The encoding of both the hash and signature, such as "base64", "hex", etc. is passed in encoding. The ECDSA public key is passed in the last argument (pubkey).

The method returns 1 for a valid signature, 0 for an invalid signature, and -1 for any other failure.

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