如何修复无效的AES密钥长度？
我正在eclipse上开展基于Web的文本加密和解密项目（遵循Struts 2）
每当我输入密码和纯文本时，我都会收到无效的AES密钥长度错误。
服务类（SymAES.java）
package com.anoncrypt.services; import java.security.Key; import javax.crypto.Cipher; import javax.crypto.spec.SecretKeySpec; import sun.misc.BASE64Decoder; import sun.misc.BASE64Encoder; public class SymAES { private static final String ALGORITHM = "AES"; private static byte[] keyValue= new byte[] { 'T', 'h', 'i', 's', 'I', 's', 'A', 'S', 'e', 'c', 'r', 'e', 't', 'K', 'e', 'y' }; public String encode(String valueToEnc) throws Exception { System.out.println("The Key byte value"+keyValue ); Key key = generateKey(); Cipher c = Cipher.getInstance(ALGORITHM); c.init(Cipher.ENCRYPT_MODE, key); byte[] encValue = c.doFinal(valueToEnc.getBytes()); String encryptedValue = new BASE64Encoder().encode(encValue); return encryptedValue; } public String decode(String encryptedValue) throws Exception { Key key = generateKey(); Cipher c = Cipher.getInstance(ALGORITHM); c.init(Cipher.DECRYPT_MODE, key); byte[] decordedValue = new BASE64Decoder().decodeBuffer(encryptedValue); byte[] decValue = c.doFinal(decordedValue); String decryptedValue = new String(decValue); return decryptedValue; } private static Key generateKey() throws Exception { //System.out.println("passs value"+pass); System.out.println("The Key byte value instde genkey"+keyValue ); Key key = new SecretKeySpec(keyValue, ALGORITHM); return key; } public void start(String passcode)throws Exception { keyValue = passcode.getBytes(); System.out.println("passcode"+passcode); System.out.println("The Key byte value inside start"+keyValue ); } } 这是Action类（SymEncrypt.java）
package com.anoncrypt.actions; import com.anoncrypt.services.SymAES; public class SymEncrypt { private String encrypt; private String encrypted; private String password; boolean TEMP; public String execute() throws Exception { SymAES ob=new SymAES(); ob.start(getPassword()); setEncrypted( ob.encode(getEncrypt())); System.out.println("into action class "+getEncrypted()); if(getEncrypted().equals(null)) return "error"; else return "success"; } public String getEncrypted() { return encrypted; } public void setEncrypted(String encrypted) { this.encrypted = encrypted; } public String getEncrypt() { return encrypt; } public void setEncrypt(String encrypt) { this.encrypt = encrypt; } public String getPassword() { return password; } public void setPassword(String password) { this.password = password; } }
这就是错误
java.security.InvalidKeyException: Invalid AES key length: 6 bytes com.sun.crypto.provider.AESCrypt.init(AESCrypt.java:87) com.sun.crypto.provider.ElectronicCodeBook.init(ElectronicCodeBook.java:93) com.sun.crypto.provider.CipherCore.init(CipherCore.java:582) com.sun.crypto.provider.CipherCore.init(CipherCore.java:458) com.sun.crypto.provider.AESCipher.engineInit(AESCipher.java:307) javax.crypto.Cipher.implInit(Cipher.java:797) javax.crypto.Cipher.chooseProvider(Cipher.java:859) javax.crypto.Cipher.init(Cipher.java:1229) javax.crypto.Cipher.init(Cipher.java:1166) com.anoncrypt.services.SymAES.encode(SymAES.java:35) com.anoncrypt.actions.SymEncrypt.execute(SymEncrypt.java:24) sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) java.lang.reflect.Method.invoke(Unknown Source) ognl.OgnlRuntime.invokeMethod(OgnlRuntime.java:870) ognl.OgnlRuntime.callAppropriateMethod(OgnlRuntime.java:1293) ognl.ObjectMethodAccessor.callMethod(ObjectMethodAccessor.java:68) com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethodWithDebugInfo(XWorkMethodAccessor.java:117) com.opensymphony.xwork2.ognl.accessor.XWorkMethodAccessor.callMethod(XWorkMethodAccessor.java:108) ognl.OgnlRuntime.callMethod(OgnlRuntime.java:1369) ognl.ASTMethod.getValueBody(ASTMethod.java:90) ognl.SimpleNode.evaluateGetValueBody(SimpleNode.java:212) ognl.SimpleNode.getValue(SimpleNode.java:258) ognl.Ognl.getValue(Ognl.java:494) ognl.Ognl.getValue(Ognl.java:458) com.opensymphony.xwork2.ognl.OgnlUtil$2.execute(OgnlUtil.java:309) com.opensymphony.xwork2.ognl.OgnlUtil.compileAndExecute(OgnlUtil.java:340) com.opensymphony.xwork2.ognl.OgnlUtil.getValue(OgnlUtil.java:307) com.opensymphony.xwork2.DefaultActionInvocation.invokeAction(DefaultActionInvocation.java:423) com.opensymphony.xwork2.DefaultActionInvocation.invokeActionOnly(DefaultActionInvocation.java:287) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:250) org.apache.struts2.interceptor.DeprecationInterceptor.intercept(DeprecationInterceptor.java:41) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.debugging.DebuggingInterceptor.intercept(DebuggingInterceptor.java:256) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor.doIntercept(DefaultWorkflowInterceptor.java:167) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.validator.ValidationInterceptor.doIntercept(ValidationInterceptor.java:265) org.apache.struts2.interceptor.validation.AnnotationValidationInterceptor.doIntercept(AnnotationValidationInterceptor.java:76) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ConversionErrorInterceptor.intercept(ConversionErrorInterceptor.java:138) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ParametersInterceptor.doIntercept(ParametersInterceptor.java:229) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.StaticParametersInterceptor.intercept(StaticParametersInterceptor.java:191) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.MultiselectInterceptor.intercept(MultiselectInterceptor.java:73) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.DateTextFieldInterceptor.intercept(DateTextFieldInterceptor.java:125) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.CheckboxInterceptor.intercept(CheckboxInterceptor.java:91) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.FileUploadInterceptor.intercept(FileUploadInterceptor.java:253) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ModelDrivenInterceptor.intercept(ModelDrivenInterceptor.java:100) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ScopedModelDrivenInterceptor.intercept(ScopedModelDrivenInterceptor.java:141) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ChainingInterceptor.intercept(ChainingInterceptor.java:145) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.PrepareInterceptor.doIntercept(PrepareInterceptor.java:171) com.opensymphony.xwork2.interceptor.MethodFilterInterceptor.intercept(MethodFilterInterceptor.java:98) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.I18nInterceptor.intercept(I18nInterceptor.java:139) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.interceptor.ServletConfigInterceptor.intercept(ServletConfigInterceptor.java:164) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.AliasInterceptor.intercept(AliasInterceptor.java:193) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) com.opensymphony.xwork2.interceptor.ExceptionMappingInterceptor.intercept(ExceptionMappingInterceptor.java:189) com.opensymphony.xwork2.DefaultActionInvocation.invoke(DefaultActionInvocation.java:244) org.apache.struts2.impl.StrutsActionProxy.execute(StrutsActionProxy.java:54) org.apache.struts2.dispatcher.Dispatcher.serviceAction(Dispatcher.java:564) org.apache.struts2.dispatcher.ng.ExecuteOperations.executeAction(ExecuteOperations.java:81) org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:99)
AES仅支持16,24或32字节的密钥大小。 您需要准确提供该金额，或者从键入的内容中获取密钥。
从密码短语中导出密钥的方法有很多种。 Java为此目的提供了PBKDF2实现。
我使用erickson的答案绘制完整的图片（仅加密，因为解密类似，但包括拆分密文）：
SecureRandom random = new SecureRandom(); byte[] salt = new byte[16]; random.nextBytes(salt); KeySpec spec = new PBEKeySpec("password".toCharArray(), salt, 65536, 256); // AES-256 SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1"); byte[] key = f.generateSecret(spec).getEncoded(); byte[] ivBytes = new byte[16]; random.nextBytes(ivBytes); IvParameterSpec iv = new IvParameterSpec(ivBytes); Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding"); c.init(Cipher.ENCRYPT_MODE, key, iv); byte[] encValue = c.doFinal(valueToEnc.getBytes()); byte[] finalCiphertext = new byte[encValue.length+2*16]; System.arraycopy(ivBytes, 0, finalCiphertext, 0, 16); System.arraycopy(salt, 0, finalCiphertext, 16, 16); System.arraycopy(encValue, 0, finalCiphertext, 32, encValue.length); return finalCiphertext;
其他要记住的事项：
- 始终使用完全限定的密码名称。 在这种情况下，
AES并不合适，因为不同的JVM / JCE提供程序可能会对操作模式和填充使用不同的默认值。 使用AES/CBC/PKCS5Padding。 不要使用ECB模式，因为它在语义上不安全。 - 如果您不使用ECB模式，则需要将IV与密文一起发送。 这通常通过将IV添加到密文字节数组来完成。 IV会自动为您创建，您可以通过
cipherInstance.getIV()获取它。 - 每当你发送东西时，你需要确保它一直没有改变。 很难用MAC正确实现加密。 我建议您使用CCM或GCM等经过身份validation的模式。
您可以validation密钥长度限制：
int maxKeyLen = Cipher.getMaxAllowedKeyLength("AES"); System.out.println("MaxAllowedKeyLength=[" + maxKeyLen + "].");
我遇到了同样的问题，然后我把我的密钥写成16字节，现在它正常工作。 准确地创建16字节的密钥。 它肯定会奏效。