diff --git a/src/api/addAttachedSignature.test.ts b/src/api/addAttachedSignature.test.ts
new file mode 100644
index 0000000..620a696
--- /dev/null
+++ b/src/api/addAttachedSignature.test.ts
@@ -0,0 +1,88 @@
+import 'cadesplugin';
+import { rawCertificates, parsedCertificates } from '../__mocks__/certificates';
+import { createAttachedSignature } from './createAttachedSignature';
+import { _getCadesCert } from '../helpers/_getCadesCert';
+import { addAttachedSignature } from './addAttachedSignature';
+
+const [rawCertificateMock] = rawCertificates;
+const [parsedCertificateMock] = parsedCertificates;
+
+jest.mock('../helpers/_getCadesCert', () => ({ _getCadesCert: jest.fn(() => rawCertificateMock) }));
+
+beforeEach(() => {
+  (_getCadesCert as jest.Mock).mockClear();
+});
+
+const executionSteps = [
+  Symbol('step 0'),
+  Symbol('step 1'),
+  Symbol('step 2'),
+  Symbol('step 3'),
+  Symbol('step 4'),
+  Symbol('step 5'),
+];
+
+const executionFlow = {
+  [executionSteps[0]]: {
+    propset_Name: jest.fn(),
+    propset_Value: jest.fn(),
+  },
+  [executionSteps[1]]: {
+    propset_ContentEncoding: jest.fn(),
+    propset_Content: jest.fn(),
+    SignCades: jest.fn(() => executionSteps[4]),
+    CoSignCades: jest.fn(() => executionSteps[5]),
+  },
+  [executionSteps[2]]: {
+    propset_Certificate: jest.fn(),
+    AuthenticatedAttributes2: executionSteps[3],
+    propset_Options: jest.fn(),
+  },
+  [executionSteps[3]]: {
+    Add: jest.fn(),
+  },
+  [executionSteps[4]]: 'signature',
+  [executionSteps[5]]: 'newSignature',
+};
+
+window.cadesplugin.__defineExecutionFlow(executionFlow);
+window.cadesplugin.CreateObjectAsync.mockImplementation((object) => {
+  switch (object) {
+    case 'CADESCOM.CPAttribute':
+      return executionSteps[0];
+    case 'CAdESCOM.CadesSignedData':
+      return executionSteps[1];
+    case 'CAdESCOM.CPSigner':
+      return executionSteps[2];
+  }
+});
+
+describe('addAttachedSignature', () => {
+  test('uses Buffer to encrypt the message', async () => {
+    const originalBufferFrom = global.Buffer.from;
+
+    (global.Buffer.from as jest.Mock) = jest.fn(() => ({
+      toString: jest.fn(),
+    }));
+
+    await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+    await addAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect(global.Buffer.from).toHaveBeenCalledTimes(2);
+
+    global.Buffer.from = originalBufferFrom;
+  });
+
+  test('uses specified certificate', async () => {
+    await addAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect(_getCadesCert).toHaveBeenCalledWith(parsedCertificateMock.thumbprint);
+  });
+
+  test('returns new signature', async () => {
+    await createAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+    const signature = await addAttachedSignature(parsedCertificateMock.thumbprint, 'message');
+
+    expect(signature).toEqual('newSignature');
+  });
+});
diff --git a/src/api/addAttachedSignature.ts b/src/api/addAttachedSignature.ts
new file mode 100644
index 0000000..f9d2f0a
--- /dev/null
+++ b/src/api/addAttachedSignature.ts
@@ -0,0 +1,86 @@
+import { CADESCOM_AUTHENTICATED_ATTRIBUTE_SIGNING_TIME } from '../constants';
+import { _afterPluginsLoaded } from '../helpers/_afterPluginsLoaded';
+import { _extractMeaningfulErrorMessage } from '../helpers/_extractMeaningfulErrorMessage';
+import { __cadesAsyncToken__, __createCadesPluginObject__, _generateCadesFn } from '../helpers/_generateCadesFn';
+import { _getCadesCert } from '../helpers/_getCadesCert';
+import { _getDateObj } from '../helpers/_getDateObj';
+
+/**
+ * Создает присоединенную подпись сообщения по отпечатку сертификата
+ *
+ * @param thumbprint - отпечаток сертификата
+ * @param message - подписываемое сообщение
+ * @returns подпись в формате PKCS#7
+ */
+export const addAttachedSignature = _afterPluginsLoaded(
+  async (thumbprint: string, unencryptedMessage: string | ArrayBuffer): Promise<string> => {
+    const { cadesplugin } = window;
+    const cadesCertificate = await _getCadesCert(thumbprint);
+
+    return eval(
+      _generateCadesFn(function addAttachedSignature(): string {
+        let cadesAttrs;
+        let cadesSignedData;
+        let cadesSigner;
+
+        try {
+          cadesAttrs = __cadesAsyncToken__ + __createCadesPluginObject__('CADESCOM.CPAttribute');
+          cadesSignedData = __cadesAsyncToken__ + __createCadesPluginObject__('CAdESCOM.CadesSignedData');
+          cadesSigner = __cadesAsyncToken__ + __createCadesPluginObject__('CAdESCOM.CPSigner');
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при инициализации подписи');
+        }
+
+        const currentTime = _getDateObj(new Date());
+
+        try {
+          void (__cadesAsyncToken__ + cadesAttrs.propset_Name(CADESCOM_AUTHENTICATED_ATTRIBUTE_SIGNING_TIME));
+          void (__cadesAsyncToken__ + cadesAttrs.propset_Value(currentTime));
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при установке времени подписи');
+        }
+
+        let messageBase64;
+
+        try {
+          messageBase64 = Buffer.from(unencryptedMessage).toString('base64');
+        } catch (error) {
+          console.error(error);
+
+          throw new Error('Ошибка при преобразовании сообщения в Base64');
+        }
+
+        let cadesAuthAttrs;
+
+        try {
+          void (__cadesAsyncToken__ + cadesSigner.propset_Certificate(cadesCertificate));
+          cadesAuthAttrs = __cadesAsyncToken__ + cadesSigner.AuthenticatedAttributes2;
+          void (__cadesAsyncToken__ + cadesAuthAttrs.Add(cadesAttrs));
+          void (__cadesAsyncToken__ + cadesSignedData.propset_ContentEncoding(cadesplugin.CADESCOM_BASE64_TO_BINARY));
+          void (__cadesAsyncToken__ + cadesSignedData.propset_Content(messageBase64));
+          void (__cadesAsyncToken__ + cadesSigner.propset_Options(cadesplugin.CAPICOM_CERTIFICATE_INCLUDE_WHOLE_CHAIN));
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при указании данных для подписи');
+        }
+
+        let signature: string;
+
+        try {
+          signature = __cadesAsyncToken__ + cadesSignedData.CoSignCades(cadesSigner, cadesplugin.CADESCOM_PKCS7_TYPE);
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при подписании данных');
+        }
+
+        return signature;
+      }),
+    );
+  },
+);
diff --git a/src/api/addDetachedSignature.test.ts b/src/api/addDetachedSignature.test.ts
new file mode 100644
index 0000000..70d289e
--- /dev/null
+++ b/src/api/addDetachedSignature.test.ts
@@ -0,0 +1,81 @@
+import 'cadesplugin';
+import { rawCertificates, parsedCertificates } from '../__mocks__/certificates';
+import { createDetachedSignature } from './createDetachedSignature';
+import { _getCadesCert } from '../helpers/_getCadesCert';
+import { addDetachedSignature } from "./addDetachedSignature";
+
+const [rawCertificateMock] = rawCertificates;
+const [parsedCertificateMock] = parsedCertificates;
+
+jest.mock('../helpers/_getCadesCert', () => ({ _getCadesCert: jest.fn(() => rawCertificateMock) }));
+
+beforeEach(() => {
+  (_getCadesCert as jest.Mock).mockClear();
+});
+
+const executionSteps = [
+  Symbol('step 0'),
+  Symbol('step 1'),
+  Symbol('step 2'),
+  Symbol('step 3'),
+  Symbol('step 4'),
+  Symbol('step 5'),
+  Symbol('step 6'),
+];
+
+const executionFlow = {
+  [executionSteps[0]]: {
+    propset_Name: jest.fn(),
+    propset_Value: jest.fn(),
+  },
+  [executionSteps[1]]: {
+    propset_ContentEncoding: jest.fn(),
+    propset_Content: jest.fn(),
+    SignHash: jest.fn(() => executionSteps[4]),
+    CoSignHash: jest.fn(() => executionSteps[6]),
+  },
+  [executionSteps[2]]: {
+    propset_Certificate: jest.fn(),
+    AuthenticatedAttributes2: executionSteps[3],
+    propset_Options: jest.fn(),
+  },
+  [executionSteps[3]]: {
+    Add: jest.fn(),
+  },
+  [executionSteps[4]]: 'signature',
+  [executionSteps[5]]: {
+    propset_Algorithm: jest.fn(),
+    SetHashValue: jest.fn(),
+  },
+  [executionSteps[6]]: 'newSignature',
+};
+
+window.cadesplugin.__defineExecutionFlow(executionFlow);
+window.cadesplugin.CreateObjectAsync.mockImplementation((object) => {
+  switch (object) {
+    case 'CADESCOM.CPAttribute':
+      return executionSteps[0];
+    case 'CAdESCOM.CadesSignedData':
+      return executionSteps[1];
+    case 'CAdESCOM.CPSigner':
+      return executionSteps[2];
+    case 'CAdESCOM.HashedData':
+      return executionSteps[5];
+  }
+});
+
+describe('addDetachedSignature', () => {
+  test('uses specified certificate', async () => {
+    const signature = await createDetachedSignature(parsedCertificateMock.thumbprint, 'message');
+    await addDetachedSignature(parsedCertificateMock.thumbprint, signature);
+
+    expect(_getCadesCert).toHaveBeenCalledWith(parsedCertificateMock.thumbprint);
+  });
+
+  test('returns new signature', async () => {
+    let signature = await createDetachedSignature(parsedCertificateMock.thumbprint, 'message');
+    signature = await addDetachedSignature(parsedCertificateMock.thumbprint, signature);
+
+    expect(signature).toEqual('newSignature');
+  });
+});
diff --git a/src/api/addDetachedSignature.ts b/src/api/addDetachedSignature.ts
new file mode 100644
index 0000000..adfa75c
--- /dev/null
+++ b/src/api/addDetachedSignature.ts
@@ -0,0 +1,90 @@
+import { CADESCOM_AUTHENTICATED_ATTRIBUTE_SIGNING_TIME } from '../constants';
+import { _afterPluginsLoaded } from '../helpers/_afterPluginsLoaded';
+import { _extractMeaningfulErrorMessage } from '../helpers/_extractMeaningfulErrorMessage';
+import { __cadesAsyncToken__, __createCadesPluginObject__, _generateCadesFn } from '../helpers/_generateCadesFn';
+import { _getCadesCert } from '../helpers/_getCadesCert';
+import { _getDateObj } from '../helpers/_getDateObj';
+
+/**
+ * Создает отсоединенную подпись хеша по отпечатку сертификата
+ *
+ * @param thumbprint - отпечаток сертификата
+ * @param messageHash - хеш подписываемого сообщения, сгенерированный по ГОСТ Р 34.11-2012 256 бит
+ * @returns подпись в формате PKCS#7
+ */
+export const addDetachedSignature = _afterPluginsLoaded(
+  async (thumbprint: string, messageHash: string): Promise<string> => {
+    const { cadesplugin } = window;
+    const cadesCertificate = await _getCadesCert(thumbprint);
+
+    return eval(
+      _generateCadesFn(function addDetachedSignature(): string {
+        let cadesAttrs;
+        let cadesHashedData;
+        let cadesSignedData;
+        let cadesSigner;
+
+        try {
+          cadesAttrs = __cadesAsyncToken__ + __createCadesPluginObject__('CADESCOM.CPAttribute');
+          cadesHashedData = __cadesAsyncToken__ + __createCadesPluginObject__('CAdESCOM.HashedData');
+          cadesSignedData = __cadesAsyncToken__ + __createCadesPluginObject__('CAdESCOM.CadesSignedData');
+          cadesSigner = __cadesAsyncToken__ + __createCadesPluginObject__('CAdESCOM.CPSigner');
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при инициализации подписи');
+        }
+
+        const currentTime = _getDateObj(new Date());
+
+        try {
+          void (__cadesAsyncToken__ + cadesAttrs.propset_Name(CADESCOM_AUTHENTICATED_ATTRIBUTE_SIGNING_TIME));
+          void (__cadesAsyncToken__ + cadesAttrs.propset_Value(currentTime));
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при установке времени подписи');
+        }
+
+        let cadesAuthAttrs;
+
+        try {
+          void (__cadesAsyncToken__ + cadesSigner.propset_Certificate(cadesCertificate));
+          cadesAuthAttrs = __cadesAsyncToken__ + cadesSigner.AuthenticatedAttributes2;
+          void (__cadesAsyncToken__ + cadesAuthAttrs.Add(cadesAttrs));
+          void (__cadesAsyncToken__ + cadesSigner.propset_Options(cadesplugin.CAPICOM_CERTIFICATE_INCLUDE_WHOLE_CHAIN));
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при установке сертификата');
+        }
+
+        try {
+          void (
+            __cadesAsyncToken__ +
+            cadesHashedData.propset_Algorithm(cadesplugin.CADESCOM_HASH_ALGORITHM_CP_GOST_3411_2012_256)
+          );
+          void (__cadesAsyncToken__ + cadesHashedData.SetHashValue(messageHash));
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при установке хеша');
+        }
+
+        let signature: string;
+
+        try {
+          signature =
+            __cadesAsyncToken__ +
+            cadesSignedData.CoSignHash(cadesHashedData, cadesSigner, cadesplugin.CADESCOM_PKCS7_TYPE);
+        } catch (error) {
+          console.error(error);
+
+          throw new Error(_extractMeaningfulErrorMessage(error) || 'Ошибка при подписании данных');
+        }
+
+        return signature;
+      }),
+    );
+  },
+);