### Install gost-crypto

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Installs the gost-crypto library using go get.

```go
go get github.com/rekurt/gost-crypto

```

--------------------------------

### Example Output

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Demonstrates the expected output for a successful verification.

```text
Output:
valid: true

```

--------------------------------

### Sign and Verify with gost-crypto

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Demonstrates generating a key pair, signing a message, and verifying the signature using gost-crypto. Ensures proper key management with Zeroize.

```go
package main

import (
    "fmt"
    gostcrypto "github.com/rekurt/gost-crypto"
)

func main() {
    priv, err := gostcrypto.GenerateKey(gostcrypto.CurveTC26_256_A)
    if err != nil {
        panic(err)
    }
    defer priv.Zeroize()

    sig, err := gostcrypto.Sign(priv, []byte("Hello, GOST!"))
    if err != nil {
        panic(err)
    }

    ok, err := gostcrypto.Verify(priv.PublicKey(), []byte("Hello, GOST!"), sig)
    if err != nil {
        panic(err)
    }
    fmt.Println("valid:", ok) // valid: true
}

```

--------------------------------

### LoadPrivKey

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Creates a GOST R 34.10-2012 private key from raw bytes. The raw bytes must be big-endian and match the key size for the curve.

```APIDOC
## LoadPrivKey

### Description
Creates a GOST R 34.10-2012 private key from raw bytes. The raw bytes must be big-endian and exactly the key size for the curve (32 bytes for 256-bit curves, 64 bytes for 512-bit curves).

### Method
N/A (Function signature provided)

### Signature
`func LoadPrivKey(c Curve, raw []byte) (*PrivKey, error)`

### Parameters
#### Input Parameters
- **c** (Curve) - The curve associated with the private key.
- **raw** ([]byte) - The raw private key bytes (big-endian).

#### Return Values
- (*PrivKey) - The loaded private key.
- (error) - An error if loading the private key fails.
```

--------------------------------

### Key Generation and Loading

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Provides functionality to generate new cryptographic key pairs or load existing private keys.

```APIDOC
## Key Generation and Loading

### Description
Provides functionality to generate new cryptographic key pairs or load existing private keys.

### Functions

#### GenerateKey

* **Signature:** `func GenerateKey(c Curve) (*PrivKey, error)`
* **Description:** Generates a new private key for the specified curve.
* **Parameters:**
  * `c` (Curve) - The cryptographic curve to use for key generation.
* **Returns:**
  * `*PrivKey` - The newly generated private key.
  * `error` - An error if key generation fails.

#### LoadPrivKey

* **Signature:** `func LoadPrivKey(c Curve, raw []byte) (*PrivKey, error)`
* **Description:** Loads a private key from raw byte data for the specified curve.
* **Parameters:**
  * `c` (Curve) - The cryptographic curve of the private key.
  * `raw` ([]byte) - The raw byte representation of the private key.
* **Returns:**
  * `*PrivKey` - The loaded private key.
  * `error` - An error if loading the private key fails.
```

--------------------------------

### Load GOST R 34.10-2012 Private Key

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Creates a GOST R 34.10-2012 private key from raw big-endian bytes. The byte slice must match the key size for the curve.

```go
func LoadPrivKey(c Curve, raw []byte) (*PrivKey, error)
```

--------------------------------

### Generate Key Pair and Sign Message

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Generates a new key pair using a specified curve and signs a message. Ensure to handle errors and zeroize the private key after use.

```go
priv, err := gostcrypto.GenerateKey(gostcrypto.CurveTC26_256_A)
if err != nil {
    log.Fatal(err)
}
defer priv.Zeroize()

sig, err := gostcrypto.Sign(priv, []byte("Hello, GOST!"))
if err != nil {
    log.Fatal(err)
}

ok, err := gostcrypto.Verify(priv.PublicKey(), []byte("Hello, GOST!"), sig)

```

--------------------------------

### Agree

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Performs GOST VKO key agreement between a local private key and a remote peer's public key. The ukm (User Keying Material) is required and must be non-empty. This function is symmetric.

```APIDOC
## Agree

### Description
Performs GOST VKO key agreement between a local private key and a remote peer's public key. The ukm (User Keying Material) is required and must be non-empty. Agree is symmetric.

### Method
N/A (Function signature provided)

### Signature
`func Agree(priv *PrivKey, pub *PubKey, ukm []byte) ([]byte, error)`

### Parameters
#### Input Parameters
- **priv** (*PrivKey) - The local private key.
- **pub** (*PubKey) - The remote peer's public key.
- **ukm** ([]byte) - User Keying Material. Must be non-empty.

#### Return Values
- ([]byte) - The shared secret.
- (error) - An error if the key agreement fails.
```

--------------------------------

### Key Agreement

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Performs key agreement using GOST R 34.10-2012 ECDH.

```APIDOC
## Key Agreement

### Description
Performs key agreement using GOST R 34.10-2012 ECDH.

### Function

#### Agree

* **Signature:** `func Agree(priv *PrivKey, pub *PubKey, ukm []byte) ([]byte, error)`
* **Description:** Computes a shared secret using the private key of one party, the public key of the other party, and an optional User Keying Material (UKM).
* **Parameters:**
  * `priv` (*PrivKey) - The private key of the local party.
  * `pub` (*PubKey) - The public key of the remote party.
  * `ukm` ([]byte) - Optional User Keying Material.
* **Returns:**
  * `[]byte` - The computed shared secret.
  * `error` - An error if key agreement fails.
```

--------------------------------

### VKO Key Agreement with gost-crypto

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Performs VKO (key agreement) between two parties using their private and public keys. Demonstrates that the shared secret is symmetric regardless of the order of agreement.

```go
privA, _ := gostcrypto.GenerateKey(gostcrypto.CurveTC26_256_A)
privB, _ := gostcrypto.GenerateKey(gostcrypto.CurveTC26_256_A)
deffer privA.Zeroize()
deffer privB.Zeroize()

ukm := []byte{0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08}

// Shared secret is symmetric: Agree(A, pubB) == Agree(B, pubA)
secretAB, _ := gostcrypto.Agree(privA, privB.PublicKey(), ukm)
secretBA, _ := gostcrypto.Agree(privB, privA.PublicKey(), ukm)
// bytes.Equal(secretAB, secretBA) == true

```

--------------------------------

### Kuznechik Encryption (AEAD) with gost-crypto

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Shows how to perform authenticated encryption using the Kuznechik block cipher in MGM mode. Requires a 32-byte key and generates a nonce for sealing plaintext.

```go
import "github.com/rekurt/gost-crypto/pkg/gost3413"

aead, _ := gost3413.NewMGMFromKey(key) // 32-byte key

nonce := make([]byte, aead.NonceSize())
rand.Read(nonce)

ciphertext := aead.Seal(nil, nonce, plaintext, additionalData)


```

--------------------------------

### Retrieve All TC26 Curves

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Returns a slice containing all eight supported TC26 parameter sets.

```go
func AllCurves() []Curve
```

--------------------------------

### Verify

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Hashes a message using Streebog and verifies a GOST R 34.10-2012 signature. The hash size is automatically determined by the key's curve.

```APIDOC
## Verify

### Description
Hashes msg with Streebog and verifies a GOST R 34.10-2012 signature. The hash size is chosen automatically based on the key's curve: Streebog-256 for 256-bit curves, Streebog-512 for 512-bit curves.

### Method
N/A (Function signature provided)

### Signature
`func Verify(pub *PubKey, msg, sig []byte) (bool, error)`

### Parameters
#### Input Parameters
- **pub** (*PubKey) - The public key to use for verification.
- **msg** ([]byte) - The original message.
- **sig** ([]byte) - The signature to verify.

#### Return Values
- (bool) - True if the signature is valid, false otherwise.
- (error) - An error if verification fails.
```

--------------------------------

### TC26 Parameter Set Constants

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Defines constants for TC26 parameter sets, re-exported from the pkg/gost3410 package.

```go
const (
	CurveTC26_256_A = gost3410.CurveTC26_256_A // id-tc26-gost-3410-2012-256-paramSetA
	CurveTC26_256_B = gost3410.CurveTC26_256_B // id-tc26-gost-3410-2012-256-paramSetB
	CurveTC26_256_C = gost3410.CurveTC26_256_C // id-tc26-gost-3410-2012-256-paramSetC
	CurveTC26_256_D = gost3410.CurveTC26_256_D // id-tc26-gost-3410-2012-256-paramSetD
	CurveTC26_512_A = gost3410.CurveTC26_512_A // id-tc26-gost-3410-2012-512-paramSetA
	CurveTC26_512_B = gost3410.CurveTC26_512_B // id-tc26-gost-3410-2012-512-paramSetB
	CurveTC26_512_C = gost3410.CurveTC26_512_C // id-tc26-gost-3410-2012-512-paramSetC
	CurveTC26_512_D = gost3410.CurveTC26_512_D // id-tc26-gost-3410-2012-512-paramSetD
)
```

--------------------------------

### Verify Signature

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Verifies a signature against a public key and the original message. Handles potential errors during verification.

```go
ok, err := gostcrypto.Verify(pub, []byte("Hello, GOST!"), sig)

```

--------------------------------

### Sign and Verify

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Signs a message using a private key and verifies a signature using a public key. The hash function (Streebog-256 or Streebog-512) is automatically selected based on the key's curve size.

```APIDOC
## Sign and Verify

### Description
Signs a message using a private key and verifies a signature using a public key. The hash function (Streebog-256 or Streebog-512) is automatically selected based on the key's curve size.

### Functions

#### Sign

* **Signature:** `func Sign(priv *PrivKey, msg []byte) ([]byte, error)`
* **Description:** Signs the given message using the provided private key.
* **Parameters:**
  * `priv` (*PrivKey) - The private key to use for signing.
  * `msg` ([]byte) - The message to sign.
* **Returns:**
  * `[]byte` - The signature.
  * `error` - An error if signing fails.

#### Verify

* **Signature:** `func Verify(pub *PubKey, msg, sig []byte) (bool, error)`
* **Description:** Verifies the given signature against the message using the provided public key.
* **Parameters:**
  * `pub` (*PubKey) - The public key to use for verification.
  * `msg` ([]byte) - The original message.
  * `sig` ([]byte) - The signature to verify.
* **Returns:**
  * `bool` - True if the signature is valid, false otherwise.
  * `error` - An error if verification fails.
```

--------------------------------

### Hashing

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Provides functions to compute hash sums using Streebog-256 and Streebog-512 algorithms.

```APIDOC
## Hashing

### Description
Provides functions to compute hash sums using Streebog-256 and Streebog-512 algorithms.

### Functions

#### HashSum256

* **Signature:** `func HashSum256(data []byte) [32]byte`
* **Description:** Computes the Streebog-256 hash of the input data.
* **Parameters:**
  * `data` ([]byte) - The data to hash.
* **Returns:**
  * `[32]byte` - The 32-byte hash sum.

#### HashSum512

* **Signature:** `func HashSum512(data []byte) [64]byte`
* **Description:** Computes the Streebog-512 hash of the input data.
* **Parameters:**
  * `data` ([]byte) - The data to hash.
* **Returns:**
  * `[64]byte` - The 64-byte hash sum.
```

--------------------------------

### GOST VKO Key Agreement

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Performs GOST VKO key agreement. Requires a non-empty User Keying Material (ukm). The operation is symmetric.

```go
func Agree(priv *PrivKey, pub *PubKey, ukm []byte) ([]byte, error)
```

--------------------------------

### Sign

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Hashes a message using Streebog and signs it with GOST R 34.10-2012. The hash size is automatically determined by the key's curve.

```APIDOC
## Sign

### Description
Hashes msg with Streebog and signs with GOST R 34.10-2012. The hash size is chosen automatically based on the key's curve: Streebog-256 for 256-bit curves, Streebog-512 for 512-bit curves.

### Method
N/A (Function signature provided)

### Signature
`func Sign(priv *PrivKey, msg []byte) ([]byte, error)`

### Parameters
#### Input Parameters
- **priv** (*PrivKey) - The private key to use for signing.
- **msg** ([]byte) - The message to sign.

#### Return Values
- ([]byte) - The signature.
- (error) - An error if signing fails.
```

--------------------------------

### Curves

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Provides access to all standardized TC26 elliptic curve parameter sets.

```APIDOC
## Curves

### Description
Provides access to all standardized TC26 elliptic curve parameter sets.

### Function

#### AllCurves

* **Signature:** `func AllCurves() []Curve`
* **Description:** Returns a slice containing all 8 standardized TC26 elliptic curve parameter sets (4 for 256-bit and 4 for 512-bit).
* **Returns:**
  * `[]Curve` - A slice of all supported `Curve` types.
```

--------------------------------

### Sentinel Errors

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Re-exports sentinel errors from the pkg/gost3410 package for error handling.

```go
var (
	ErrUnknownCurve     = gost3410.ErrUnknownCurve
	ErrPointNotOnCurve  = gost3410.ErrPointNotOnCurve
	ErrInvalidKeySize   = gost3410.ErrInvalidKeySize
	ErrInvalidSignature = gost3410.ErrInvalidSignature
	ErrNilKey           = gost3410.ErrNilKey
	ErrCurveMismatch    = gost3410.ErrCurveMismatch
	ErrEmptyUKM         = gost3410.ErrEmptyUKM
)
```

--------------------------------

### Streebog-256 Hash Calculation

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Calculates the Streebog-256 digest of the provided data.

```go
func HashSum256(data []byte) [32]byte
```

--------------------------------

### GOST R 34.10-2012 Private Key Type

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Defines the PrivKey type for GOST R 34.10-2012 private keys. This is an alias for gost3410.PrivKey.

```go
type PrivKey = gost3410.PrivKey
```

--------------------------------

### GOST R 34.10-2012 Signature Generation

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Hashes a message using Streebog and signs it with GOST R 34.10-2012. The hash size is automatically selected based on the key's curve.

```go
func Sign(priv *PrivKey, msg []byte) ([]byte, error)
```

--------------------------------

### GenerateKey

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Generates a new GOST R 34.10-2012 key pair for the specified curve.

```APIDOC
## GenerateKey

### Description
Generates a new GOST R 34.10-2012 key pair for the given curve.

### Method
N/A (Function signature provided)

### Signature
`func GenerateKey(c Curve) (*PrivKey, error)`

### Parameters
#### Input Parameters
- **c** (Curve) - The curve to generate the key pair for.

#### Return Values
- (*PrivKey) - The generated private key (which also contains the public key).
- (error) - An error if key generation fails.
```

--------------------------------

### Streebog-512 Hash Calculation

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Calculates the Streebog-512 digest of the provided data.

```go
func HashSum512(data []byte) [64]byte
```

--------------------------------

### GOST R 34.10-2012 Public Key Type

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Defines the PubKey type for GOST R 34.10-2012 public keys. This is an alias for gost3410.PubKey.

```go
type PubKey = gost3410.PubKey
```

--------------------------------

### Generate GOST R 34.10-2012 Key Pair

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Generates a new GOST R 34.10-2012 key pair for the specified curve.

```go
func GenerateKey(c Curve) (*PrivKey, error)
```

--------------------------------

### HashSum512

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Calculates the Streebog-512 digest of the provided data.

```APIDOC
## HashSum512

### Description
Returns the Streebog-512 digest of data.

### Method
N/A (Function signature provided)

### Signature
`func HashSum512(data []byte) [64]byte`

### Parameters
#### Input Parameters
- **data** ([]byte) - The data to hash.

#### Return Values
- ([64]byte) - The 64-byte Streebog-512 digest.
```

--------------------------------

### HashSum256

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Calculates the Streebog-256 digest of the provided data.

```APIDOC
## HashSum256

### Description
Returns the Streebog-256 digest of data.

### Method
N/A (Function signature provided)

### Signature
`func HashSum256(data []byte) [32]byte`

### Parameters
#### Input Parameters
- **data** ([]byte) - The data to hash.

#### Return Values
- ([32]byte) - The 32-byte Streebog-256 digest.
```

--------------------------------

### AllCurves

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Retrieves all eight supported TC26 parameter sets for GOST R 34.10-2012 curves.

```APIDOC
## AllCurves

### Description
Returns all eight TC26 parameter sets.

### Method
N/A (Function signature provided)

### Signature
`func AllCurves() []Curve`

### Parameters
None.

### Return Values
- ([]Curve) - A slice containing all supported `Curve` types.
```

--------------------------------

### GOST R 34.10-2012 Signature Verification

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Hashes a message using Streebog and verifies a GOST R 34.10-2012 signature. The hash size is automatically selected based on the key's curve.

```go
func Verify(pub *PubKey, msg, sig []byte) (bool, error)
```

--------------------------------

### TC26 Curve Type Definition

Source: https://pkg.go.dev/github.com/rekurt/gost-crypto

Defines the Curve type, which identifies a TC26 elliptic-curve parameter set. This is an alias for gost3410.Curve.

```go
type Curve = gost3410.Curve
```

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