Calculate a cryptographic digest (hash) of a file

Summary

The digest macro computes a cryptographic hash of a file using a specified algorithm (such as MD5, SHA-1, SHA-256, etc.). The result is returned as a hexadecimal string.

Syntax 

${digest;<algorithm>;<file>}

Parameters

  • algorithm - The digest algorithm name (e.g., “MD5”, “SHA-1”, “SHA-256”, “SHA-512”)
  • file - Path to the file to hash (relative to project directory)

Behavior

  • Reads the entire file and computes its digest
  • Uses Java’s MessageDigest API, so any supported algorithm can be used
  • Returns the digest as a lowercase hexadecimal string
  • File path is resolved relative to the project directory
  • Throws an exception if the algorithm is not supported or file cannot be read

Examples

Calculate MD5 hash:

file.md5=${digest;MD5;target/mybundle.jar}

Calculate SHA-256 hash:

file.sha256=${digest;SHA-256;LICENSE.txt}

Calculate SHA-512 for verification:

Bundle-Digest-SHA512: ${digest;SHA-512;${@}}

Multiple checksums:

md5.checksum=${digest;MD5;artifact.jar}
sha1.checksum=${digest;SHA-1;artifact.jar}
sha256.checksum=${digest;SHA-256;artifact.jar}

Use Cases

  • Generating checksums for artifact verification
  • Creating file integrity manifests
  • Implementing build reproducibility checks
  • Generating unique identifiers based on file content
  • Security verification and tamper detection
  • Creating content-addressable storage keys

Notes

  • Common algorithms include: MD5, SHA-1, SHA-256, SHA-384, SHA-512
  • The algorithm name is case-insensitive
  • MD5 and SHA-1 are considered weak for security purposes; prefer SHA-256 or stronger
  • The output is always lowercase hexadecimal
  • For large files, this reads the entire file into memory for hashing
  • See also: ${md5} and ${sha1} macros for specific algorithms

See test cases in MacroTestsForDocsExamples.java