crypto/src/main/java/org/springframework/security/crypto/encrypt/AesBytesEncryptor.java
private byte[] iv(byte[] encrypted) {
		return this.ivGenerator != NULL_IV_GENERATOR ? subArray(encrypted, 0,
				this.ivGenerator.getKeyLength()) : NULL_IV_GENERATOR.generateKey();
	}
private byte[] iv(byte[] encrypted) {
		return this.ivGenerator != NULL_IV_GENERATOR ? subArray(encrypted, 0,
				this.ivGenerator.getKeyLength()) : NULL_IV_GENERATOR.generateKey();
	}
internal helpers