TDES Decrypt

Category: Symmetric Ciphers · Node Type ID: symmetric-tdes-decrypt

Triple-DES (112 or 168-bit Key) Decryption

Overview

Decrypts ciphertext produced by TDES (3DES) Encrypt using 2-Key (16-byte) or 3-Key (24-byte) Triple-DES in CBC, ECB, CTR, CFB, or OFB mode over 8-byte blocks.

When to Use

Decrypting EMV, smartcard, or legacy financial cryptograms encrypted with 2-key or 3-key Triple-DES.

Parameter Configuration

Parameter (ID)	Type & Default	Visibility Condition	Description & Options
Cipher Mode `mode`	`select` Default: `ECB`	Always visible	Must match the Cipher Mode used during encryption (`CBC`, `ECB`, `CTR`, `CFB`, or `OFB`). See Block Cipher Modes for full details. `ECB`: ECB (Electronic Codebook) `CBC`: CBC (Cipher Block Chaining)
Padding `padding`	`select` Default: `None`	Always visible	8-byte block unpadding scheme applied after decryption in `ECB` and `CBC` modes. See Padding Schemes for full details. `None`: None `ISO7816`: ISO/IEC 9797-1 Method 2 (ISO/IEC 7816-4) `ISO97971M3`: ISO/IEC 9797-1 Method 3 `PKCS7`: PKCS#5 (RFC 2898) `ANSIX923`: ANSI X9.23
Unify Errors `errorUnify`	`boolean` Default: `false` Supports Variable Reference (`$var`: `bool`)	Always visible	Replaces built-in errors with a single custom error code/message when enabled.
Unified Error Code `errorUnifyCode`	`text` Default: `""` (empty) Supports Variable Reference (`$var`: `string`)	When `errorUnify` is `true`	Custom error code when Unify Errors is enabled.
Unified Error Message `errorUnifyMessage`	`text` Default: `""` (empty) Supports Variable Reference (`$var`: `string`)	When `errorUnify` is `true`	Custom error message when Unify Errors is enabled.

Port I/O Specification

See Ports & Connections for general wiring rules, data type colors, and dynamic port creation.

Input Ports

Port Nature: Fixed Input Ports (3 total; conditionally visible ports depend on parameter settings as shown below).

Port Name	Port ID	Data Type	Required	Visibility Condition	Description
`Key`	`key`	`Bytes` (16/24B)	Required	Always visible	TDES key: `16` bytes (2-key) or `24` bytes (3-key).
`Ciphertext`	`ciphertext`	`Bytes`	Required	Always visible	Encrypted byte array (`Uint8Array`) to decrypt.
`IV`	`iv`	`Bytes` (8B)	Optional	When `mode` is `CBC`	8-byte initialization vector used during encryption (hidden in `ECB` mode; defaults to 8 zero bytes if unconnected).

Output Ports

Port Nature: Fixed Output Ports (1 total).

Port Name	Port ID	Data Type	Visibility Condition	Description
`Plaintext`	`plaintext`	`Bytes`	Always visible	Decrypted plaintext byte array (`Uint8Array`).

Error Cases

When any of the following conditions occurs at runtime, this node transitions to an ERROR state and downstream nodes connected to its outputs do not execute. Enabling Unify Errors (errorUnify) replaces all error codes below with your configured unified error code and message.

Error Code	Default Engine Message	Trigger Condition
`INVALID_KEY_LENGTH`	Invalid key length	Raised when `Key` is neither 16 bytes nor 24 bytes.
`CIPHERTEXT_NOT_BLOCK_ALIGNED`	Ciphertext length is not a multiple of the block size	Raised in `ECB` or `CBC` mode when `Ciphertext` length is not a positive multiple of 8 bytes.
`INVALID_PADDING`	Invalid padding	Raised when the decrypted or input block's trailing bytes violate the structure of the selected padding standard.

Examples

Decrypting a 3DES-CBC Payload

Recover plaintext from a 3DES-CBC ciphertext.

Connect the 16- or 24-byte Key, 8-byte IV, and Ciphertext to TDES (3DES) Decrypt with matching Cipher Mode and Padding.