Class AesHeaderCodec

java.lang.Object

zeroecho.core.alg.aes.AesHeaderCodec

All Implemented Interfaces:

SymmetricHeaderCodec

public final class AesHeaderCodec
extends Object
implements SymmetricHeaderCodec

Minimal AES header codec that persists runtime parameters only:

IV | tagBits(pack7) | aadFlag(1) | [aadHash(32)]

• IV: 12 bytes for GCM; 16 bytes for CBC/CTR.
• tagBits: 0 for non‑GCM; otherwise 96..128.
• aadFlag: 1 when AAD is present; the header then includes a SHA‑256 of the AAD.

No algorithm magic is written. On decrypt, the codec hydrates the Conflux context with IV and tag bits and enforces AAD consistency if an AAD hash is present.

Since:

1.0

Constructor Summary

Constructors

Constructor	Description
AesHeaderCodec()	Creates a stateless AES stream-header codec.

Method Summary

Modifier and Type	Method	Description
InputStream	readHeader(InputStream in, CryptoAlgorithm algorithm, CtxInterface ctx)	Reads a header from in, updates the context with IV (and tag bits), and verifies AAD if present.
void	writeHeader(OutputStream out, CryptoAlgorithm algorithm, CtxInterface ctx)	Writes the header to out using values from the provided context.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

AesHeaderCodec

public AesHeaderCodec()

Creates a stateless AES stream-header codec.

Method Details

writeHeader

public void writeHeader(OutputStream out,
 CryptoAlgorithm algorithm,
 CtxInterface ctx)
                 throws IOException

Writes the header to out using values from the provided context.

Specified by:

writeHeader in interface SymmetricHeaderCodec

Parameters:

out - destination stream

algorithm - owning algorithm (ID "AES")

ctx - source of IV, optional tag bits, and optional AAD

Throws:

IOException - if IV is missing or an I/O error occurs

readHeader

public InputStream readHeader(InputStream in,
 CryptoAlgorithm algorithm,
 CtxInterface ctx)
                       throws IOException

Reads a header from in, updates the context with IV (and tag bits), and verifies AAD if present.

Specified by:

readHeader in interface SymmetricHeaderCodec

Parameters:

in - source stream positioned at header

algorithm - owning algorithm (ID "AES")

ctx - destination for IV/tag bits and AAD verification

Returns:

the same InputStream, positioned after the header

Throws:

IOException - on malformed header, missing AAD when required, or AAD hash mismatch