Cookbook Encode and Decode Bytestrings from Hex-Strings

data/cookbook/encode-decode-hex/hexlib.ml

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+---
+packages:
+- name: "hex"
+ tested_version: "1.5.0"
+ used_libraries:
+ - hex
+- name: "cstruct"
+ tested_version: "6.2.0"
+ used_libraries:
+ - cstruct
+discussion: |
+ - **Using the Hex and Cstruct libraries to decode a hexidecimal string to an ASCII string.
+ - **Using the Hex library to convert an ASCII string to a hexidecimal encoded message.
+ - **Uses the Hex and Cstruct libraries.
+---
+
+
+(* `decode_hex_string hex_string` is the string represented by `hex_string`.
+ Raises: Invalid_argument if `hex_string` is not valid hex. *)
+let decode_hex_string hex_string =
+ let byte_string = Hex.to_cstruct (`Hex hex_string) in
+ let decoded_string = Cstruct.to_string byte_string in
+ decoded_string
+;;
+
+(* `encode_to_hex message` is the hex string representation of `message`. *)
+let encode_to_hex message =
+ let byte_string = Cstruct.of_string message in
+ let hex_string = Hex.of_cstruct byte_string in
+ Hex.to_string hex_string
+;;
+
+(* Example usage *)
+let secret_message = "48656c6c6f2c20576f726c6421";;
+Printf.printf "Secret message: %s\n" secret_message
+
+let decrypted_message = decode_hex_string secret_message;;
+
+(* Show the decrypted message *)
+Printf.printf "Decoded message: %s\n" decrypted_message
+
+(* Encrypt the message back to hexidecimal *)
+let encoded_message = encode_to_hex secret_message;;
+
+(* Show the hexidecimal encoded message *)
+Printf.printf "Encoded message: %s\n" encoded_message;;