> ## Documentation Index
> Fetch the complete documentation index at: https://cantonfoundation-fix-875-html-entity-rendering.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# DA.Crypto.Text

> Reference documentation for Daml module DA.Crypto.Text.

<span id="module-da-crypto-text-67266" />

# DA.Crypto.Text

Functions for working with Crypto builtins.

For example, as used to implement CCTP functionality.

## Module Snapshot

<CardGroup cols={2}>
  <Card title="Lifecycle">
    Stable.
  </Card>

  <Card title="Notices">
    Status: `active`
    Introduced in: `3.4.9`
    Removed in: `-`
    Warnings: `0`
    Deprecations: `0`
    Deprecated since: `-`
  </Card>
</CardGroup>

## Data Types

<span id="type-da-crypto-text-byteshex-47880" />

### `type BytesHex = Text`

<span id="type-da-crypto-text-publickeyhex-51359" />

### `type PublicKeyHex = Text`

A DER formatted public key to be used for ECDSA signature verification

<span id="type-da-crypto-text-signaturehex-12945" />

### `type SignatureHex = Text`

A DER formatted SECP256K1 signature

## Typeclasses

<span id="class-da-crypto-text-hastohex-92431" />

### `class HasToHex a`

Methods:

* `toHex : a -> BytesHex`
  Converts a typed data value into a hex encoded string.

Instances:

* `instance HasToHex Party`
* `instance HasToHex Int`
* `instance HasToHex Text`

<span id="class-da-crypto-text-hasfromhex-84972" />

### `class HasFromHex a`

Methods:

* `fromHex : BytesHex -> a`
  Converts a hex encoded string into a typed data value.

Instances:

* `instance HasFromHex (Optional Party)`
* `instance HasFromHex (Optional Int)`
* `instance HasFromHex (Optional Text)`

## Functions

<span id="function-da-crypto-text-ishex-17968" />

### `isHex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
isHex : Text -> Bool
```

`isHex` is `True` if `t` is not empty and consists only of
hex or hexadecimal characters.

<span id="function-da-crypto-text-sha256-84499" />

### `sha256`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
sha256 : BytesHex -> BytesHex
```

Computes the SHA256 hash of the decoded UTF8 bytes of the `Text`, and returns it in its hex-encoded
form. The hex encoding uses lowercase letters.

<span id="function-da-crypto-text-keccak256-57106" />

### `keccak256`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
keccak256 : BytesHex -> BytesHex
```

Computes the KECCAK256 hash of the UTF8 bytes of the `Text`, and returns it in its hex-encoded
form. The hex encoding uses lowercase letters.

<span id="function-da-crypto-text-secp256k1withvalidation-31956" />

### `secp256k1WithValidation`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
secp256k1WithValidation : SignatureHex -> BytesHex -> PublicKeyHex -> Bool
```

Validate the SECP256K1 signature given a hex encoded message and a hex encoded DER formatted public key. Prior to
signature validation, validate the public key and check it is on the SECP256K1 curve.

<span id="function-da-crypto-text-secp256k1withecdsaonly-56908" />

### `secp256k1WithEcdsaOnly`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
secp256k1WithEcdsaOnly : SignatureHex -> BytesHex -> PublicKeyHex -> Bool
```

Validate the SECP256K1 signature given a hex encoded message and a hex encoded DER formatted public key.

<span id="function-da-crypto-text-secp256k1-38075" />

### `secp256k1`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
secp256k1 : SignatureHex -> BytesHex -> PublicKeyHex -> Bool
```

Validate the SECP256K1 signature given a SHA256 hash of a hex encoded message and a hex encoded DER formatted public key.

<span id="function-da-crypto-text-numericviastringtohex-44461" />

### `numericViaStringToHex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
numericViaStringToHex : NumericScale n => Numeric n -> BytesHex
```

<span id="function-da-crypto-text-numericviastringfromhex-60098" />

### `numericViaStringFromHex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
numericViaStringFromHex : NumericScale n => BytesHex -> Optional (Numeric n)
```

<span id="function-da-crypto-text-bytecount-29784" />

### `byteCount`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
byteCount : BytesHex -> Int
```

Number of bytes present in a byte encoded string.

<span id="function-da-crypto-text-minbytes32hex-29458" />

### `minBytes32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
minBytes32Hex : BytesHex
```

Minimum Bytes32 hex value

<span id="function-da-crypto-text-maxbytes32hex-56560" />

### `maxBytes32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
maxBytes32Hex : BytesHex
```

Maximum Bytes32 hex value

<span id="function-da-crypto-text-isbytes32hex-1801" />

### `isBytes32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
isBytes32Hex : BytesHex -> Bool
```

Validate that the byte encoded string is Bytes32Hex

<span id="function-da-crypto-text-minuint32hex-58146" />

### `minUInt32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
minUInt32Hex : BytesHex
```

Minimum UInt32 hex value

<span id="function-da-crypto-text-maxuint32hex-80016" />

### `maxUInt32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
maxUInt32Hex : BytesHex
```

Maximum UInt32 hex value

<span id="function-da-crypto-text-isuint32hex-65583" />

### `isUInt32Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
isUInt32Hex : BytesHex -> Bool
```

Validate that the byte encoded string is UInt32Hex

<span id="function-da-crypto-text-minuint64hex-67161" />

### `minUInt64Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
minUInt64Hex : BytesHex
```

Minimum UInt64 hex value

<span id="function-da-crypto-text-maxuint64hex-40555" />

### `maxUInt64Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
maxUInt64Hex : BytesHex
```

Maximum UInt64 hex value

<span id="function-da-crypto-text-isuint64hex-49912" />

### `isUInt64Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
isUInt64Hex : BytesHex -> Bool
```

Validate that the byte encoded string is UInt64Hex

<span id="function-da-crypto-text-minuint256hex-23801" />

### `minUInt256Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
minUInt256Hex : BytesHex
```

Minimum UInt256 hex value

<span id="function-da-crypto-text-maxuint256hex-58651" />

### `maxUInt256Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
maxUInt256Hex : BytesHex
```

Maximum UInt256 hex value

<span id="function-da-crypto-text-isuint256hex-33362" />

### `isUInt256Hex`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
isUInt256Hex : BytesHex -> Bool
```

Validate that the byte encoded string is UInt256Hex

<span id="function-da-crypto-text-packhexbytes-55939" />

### `packHexBytes`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
packHexBytes : BytesHex -> Int -> Optional BytesHex
```

Pack a byte encoded string to a given byte count size. If the byte string is shorter than the pad
size, then prefix with 00 byte strings. If the byte string is larger, then truncate the byte string.

<span id="function-da-crypto-text-slicehexbytes-22633" />

### `sliceHexBytes`

```daml theme={"theme":{"light":"github-light","dark":"github-dark"}}
sliceHexBytes : BytesHex -> Int -> Int -> Either Text BytesHex
```

Extract the byte string starting at startByte up to, but excluding, endByte. Byte indexing starts at 1.