credential: change git_cred to git_credentialethomson/credtype

We avoid abbreviations where possible; rename git_cred to
git_credential.

In addition, we have standardized on a trailing `_t` for enum types,
instead of using "type" in the name.  So `git_credtype_t` has become
`git_credential_t` and its members have become `GIT_CREDENTIAL` instead
of `GIT_CREDTYPE`.

Finally, the source and header files have been renamed to `credential`
instead of `cred`.

Keep previous name and values as deprecated, and include the new header
files from the previous ones.

11 files changed, 290 insertions, 184 deletions

diff --git a/include/git2.h b/include/git2.h
index 7f49f8faf..f39d7fbe2 100644
--- a/include/git2.h
+++ b/include/git2.h
@@ -22,7 +22,7 @@
 #include "git2/commit.h"
 #include "git2/common.h"
 #include "git2/config.h"
-#include "git2/cred.h"
+#include "git2/credential.h"
 #include "git2/deprecated.h"
 #include "git2/describe.h"
 #include "git2/diff.h"
diff --git a/include/git2/cred_helpers.h b/include/git2/cred_helpers.h
index 1416d5642..3721b6d8a 100644
--- a/include/git2/cred_helpers.h
+++ b/include/git2/cred_helpers.h
@@ -7,47 +7,9 @@
 #ifndef INCLUDE_git_cred_helpers_h__
 #define INCLUDE_git_cred_helpers_h__
 
-#include "transport.h"
-
-/**
- * @file git2/cred_helpers.h
- * @brief Utility functions for credential management
- * @defgroup git_cred_helpers credential management helpers
- * @ingroup Git
- * @{
- */
-GIT_BEGIN_DECL
-
-/**
- * Payload for git_cred_stock_userpass_plaintext.
- */
-typedef struct git_cred_userpass_payload {
-	const char *username;
-	const char *password;
-} git_cred_userpass_payload;
-
-
-/**
- * Stock callback usable as a git_cred_acquire_cb.  This calls
- * git_cred_userpass_plaintext_new unless the protocol has not specified
- * `GIT_CREDTYPE_USERPASS_PLAINTEXT` as an allowed type.
- *
- * @param cred The newly created credential object.
- * @param url The resource for which we are demanding a credential.
- * @param user_from_url The username that was embedded in a "user\@host"
- *                          remote url, or NULL if not included.
- * @param allowed_types A bitmask stating which cred types are OK to return.
- * @param payload The payload provided when specifying this callback.  (This is
- *        interpreted as a `git_cred_userpass_payload*`.)
- */
-GIT_EXTERN(int) git_cred_userpass(
-		git_cred **cred,
-		const char *url,
-		const char *user_from_url,
-		unsigned int allowed_types,
-		void *payload);
-
+/* These declarations have moved. */
+#ifndef GIT_DEPRECATE_HARD
+# include "git2/credential_helpers.h"
+#endif
 
-/** @} */
-GIT_END_DECL
 #endif
diff --git a/include/git2/cred.h b/include/git2/credential.h
index e89ab2361..9426a6ea2 100644
--- a/include/git2/cred.h
+++ b/include/git2/credential.h
@@ -4,15 +4,15 @@
  * This file is part of libgit2, distributed under the GNU GPL v2 with
  * a Linking Exception. For full terms see the included COPYING file.
  */
-#ifndef INCLUDE_git_cred_h__
-#define INCLUDE_git_cred_h__
+#ifndef INCLUDE_git_credential_h__
+#define INCLUDE_git_credential_h__
 
 #include "common.h"
 
 /**
- * @file git2/cred.h
+ * @file git2/credential.h
  * @brief Git authentication & credential management
- * @defgroup git_cred Authentication & credential management
+ * @defgroup git_credential Authentication & credential management
  * @ingroup Git
  * @{
  */
@@ -27,33 +27,33 @@ GIT_BEGIN_DECL
 typedef enum {
 	/**
 	 * A vanilla user/password request
-	 * @see git_cred_userpass_plaintext_new
+	 * @see git_credential_userpass_plaintext_new
 	 */
-	GIT_CREDTYPE_USERPASS_PLAINTEXT = (1u << 0),
+	GIT_CREDENTIAL_USERPASS_PLAINTEXT = (1u << 0),
 
 	/**
 	 * An SSH key-based authentication request
-	 * @see git_cred_ssh_key_new
+	 * @see git_credential_ssh_key_new
 	 */
-	GIT_CREDTYPE_SSH_KEY = (1u << 1),
+	GIT_CREDENTIAL_SSH_KEY = (1u << 1),
 
 	/**
 	 * An SSH key-based authentication request, with a custom signature
-	 * @see git_cred_ssh_custom_new
+	 * @see git_credential_ssh_custom_new
 	 */
-	GIT_CREDTYPE_SSH_CUSTOM = (1u << 2),
+	GIT_CREDENTIAL_SSH_CUSTOM = (1u << 2),
 
 	/**
 	 * An NTLM/Negotiate-based authentication request.
-	 * @see git_cred_default
+	 * @see git_credential_default
 	 */
-	GIT_CREDTYPE_DEFAULT = (1u << 3),
+	GIT_CREDENTIAL_DEFAULT = (1u << 3),
 
 	/**
 	 * An SSH interactive authentication request
-	 * @see git_cred_ssh_interactive_new
+	 * @see git_credential_ssh_interactive_new
 	 */
-	GIT_CREDTYPE_SSH_INTERACTIVE = (1u << 4),
+	GIT_CREDENTIAL_SSH_INTERACTIVE = (1u << 4),
 
 	/**
 	 * Username-only authentication request
@@ -62,9 +62,9 @@ typedef enum {
 	 * (eg. SSH, with no username in its URL) does not know which username
 	 * to use.
 	 *
-	 * @see git_cred_username_new
+	 * @see git_credential_username_new
 	 */
-	GIT_CREDTYPE_USERNAME = (1u << 5),
+	GIT_CREDENTIAL_USERNAME = (1u << 5),
 
 	/**
 	 * An SSH key-based authentication request
@@ -73,62 +73,63 @@ typedef enum {
 	 * Note that because of differences in crypto backend support, it might
 	 * not be functional.
 	 *
-	 * @see git_cred_ssh_key_memory_new
+	 * @see git_credential_ssh_key_memory_new
 	 */
-	GIT_CREDTYPE_SSH_MEMORY = (1u << 6),
-} git_credtype_t;
+	GIT_CREDENTIAL_SSH_MEMORY = (1u << 6),
+} git_credential_t;
 
 /**
  * The base structure for all credential types
  */
-typedef struct git_cred git_cred;
+typedef struct git_credential git_credential;
 
-typedef struct git_cred_userpass_plaintext git_cred_userpass_plaintext;
+typedef struct git_credential_userpass_plaintext git_credential_userpass_plaintext;
 
 /** Username-only credential information */
-typedef struct git_cred_username git_cred_username;
+typedef struct git_credential_username git_credential_username;
 
 /** A key for NTLM/Kerberos "default" credentials */
-typedef struct git_cred git_cred_default;
+typedef struct git_credential git_credential_default;
 
 /**
  * A ssh key from disk
  */
-typedef struct git_cred_ssh_key git_cred_ssh_key;
+typedef struct git_credential_ssh_key git_credential_ssh_key;
 
 /**
  * Keyboard-interactive based ssh authentication
  */
-typedef struct git_cred_ssh_interactive git_cred_ssh_interactive;
+typedef struct git_credential_ssh_interactive git_credential_ssh_interactive;
 
 /**
  * A key with a custom signature function
  */
-typedef struct git_cred_ssh_custom git_cred_ssh_custom;
+typedef struct git_credential_ssh_custom git_credential_ssh_custom;
 
 /**
  * Credential acquisition callback.
  *
  * This callback is usually involved any time another system might need
- * authentication. As such, you are expected to provide a valid git_cred
- * object back, depending on allowed_types (a git_credtype_t bitmask).
+ * authentication. As such, you are expected to provide a valid
+ * git_credential object back, depending on allowed_types (a
+ * git_credential_t bitmask).
  *
  * Note that most authentication details are your responsibility - this
  * callback will be called until the authentication succeeds, or you report
  * an error. As such, it's easy to get in a loop if you fail to stop providing
  * the same incorrect credentials.
  *
- * @param cred The newly created credential object.
+ * @param out The newly created credential object.
  * @param url The resource for which we are demanding a credential.
  * @param username_from_url The username that was embedded in a "user\@host"
  *                          remote url, or NULL if not included.
- * @param allowed_types A bitmask stating which cred types are OK to return.
+ * @param allowed_types A bitmask stating which credential types are OK to return.
  * @param payload The payload provided when specifying this callback.
  * @return 0 for success, < 0 to indicate an error, > 0 to indicate
  *       no credential was acquired
  */
-typedef int GIT_CALLBACK(git_cred_acquire_cb)(
-	git_cred **cred,
+typedef int GIT_CALLBACK(git_credential_acquire_cb)(
+	git_credential **out,
 	const char *url,
 	const char *username_from_url,
 	unsigned int allowed_types,
@@ -142,7 +143,7 @@ typedef int GIT_CALLBACK(git_cred_acquire_cb)(
  *
  * @param cred the object to free
  */
-GIT_EXTERN(void) git_cred_free(git_cred *cred);
+GIT_EXTERN(void) git_credential_free(git_credential *cred);
 
 /**
  * Check whether a credential object contains username information.
@@ -150,7 +151,7 @@ GIT_EXTERN(void) git_cred_free(git_cred *cred);
  * @param cred object to check
  * @return 1 if the credential object has non-NULL username, 0 otherwise
  */
-GIT_EXTERN(int) git_cred_has_username(git_cred *cred);
+GIT_EXTERN(int) git_credential_has_username(git_credential *cred);
 
 /**
  * Return the username associated with a credential object.
@@ -158,7 +159,7 @@ GIT_EXTERN(int) git_cred_has_username(git_cred *cred);
  * @param cred object to check
  * @return the credential username, or NULL if not applicable
  */
-GIT_EXTERN(const char *) git_cred_get_username(git_cred *cred);
+GIT_EXTERN(const char *) git_credential_get_username(git_credential *cred);
 
 /**
  * Create a new plain-text username and password credential object.
@@ -169,8 +170,8 @@ GIT_EXTERN(const char *) git_cred_get_username(git_cred *cred);
  * @param password The password of the credential.
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_userpass_plaintext_new(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_userpass_plaintext_new(
+	git_credential **out,
 	const char *username,
 	const char *password);
 
@@ -178,17 +179,22 @@ GIT_EXTERN(int) git_cred_userpass_plaintext_new(
  * Create a "default" credential usable for Negotiate mechanisms like NTLM
  * or Kerberos authentication.
  *
+ * @param out The newly created credential object.
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_default_new(git_cred **out);
+GIT_EXTERN(int) git_credential_default_new(git_credential **out);
 
 /**
  * Create a credential to specify a username.
  *
  * This is used with ssh authentication to query for the username if
  * none is specified in the url.
+ *
+ * @param out The newly created credential object.
+ * @param username The username to authenticate with
+ * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_username_new(git_cred **cred, const char *username);
+GIT_EXTERN(int) git_credential_username_new(git_credential **out, const char *username);
 
 /**
  * Create a new passphrase-protected ssh key credential object.
@@ -201,8 +207,8 @@ GIT_EXTERN(int) git_cred_username_new(git_cred **cred, const char *username);
  * @param passphrase The passphrase of the credential.
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_ssh_key_new(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_ssh_key_new(
+	git_credential **out,
 	const char *username,
 	const char *publickey,
 	const char *privatekey,
@@ -218,8 +224,8 @@ GIT_EXTERN(int) git_cred_ssh_key_new(
  * @param passphrase The passphrase of the credential.
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_ssh_key_memory_new(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_ssh_key_memory_new(
+	git_credential **out,
 	const char *username,
 	const char *publickey,
 	const char *privatekey,
@@ -235,7 +241,7 @@ typedef struct _LIBSSH2_USERAUTH_KBDINT_PROMPT LIBSSH2_USERAUTH_KBDINT_PROMPT;
 typedef struct _LIBSSH2_USERAUTH_KBDINT_RESPONSE LIBSSH2_USERAUTH_KBDINT_RESPONSE;
 #endif
 
-typedef void GIT_CALLBACK(git_cred_ssh_interactive_cb)(
+typedef void GIT_CALLBACK(git_credential_ssh_interactive_cb)(
 	const char *name,
 	int name_len,
 	const char *instruction, int instruction_len,
@@ -253,10 +259,10 @@ typedef void GIT_CALLBACK(git_cred_ssh_interactive_cb)(
  * @param payload Additional data to pass to the callback.
  * @return 0 for success or an error code for failure.
  */
-GIT_EXTERN(int) git_cred_ssh_interactive_new(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_ssh_interactive_new(
+	git_credential **out,
 	const char *username,
-	git_cred_ssh_interactive_cb prompt_callback,
+	git_credential_ssh_interactive_cb prompt_callback,
 	void *payload);
 
 /**
@@ -267,11 +273,11 @@ GIT_EXTERN(int) git_cred_ssh_interactive_new(
  * @param username username to use to authenticate
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_ssh_key_from_agent(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_ssh_key_from_agent(
+	git_credential **out,
 	const char *username);
 
-typedef int GIT_CALLBACK(git_cred_sign_cb)(
+typedef int GIT_CALLBACK(git_credential_sign_cb)(
 	LIBSSH2_SESSION *session,
 	unsigned char **sig, size_t *sig_len,
 	const unsigned char *data, size_t data_len,
@@ -295,12 +301,12 @@ typedef int GIT_CALLBACK(git_cred_sign_cb)(
  * @param payload Additional data to pass to the callback.
  * @return 0 for success or an error code for failure
  */
-GIT_EXTERN(int) git_cred_ssh_custom_new(
-	git_cred **out,
+GIT_EXTERN(int) git_credential_ssh_custom_new(
+	git_credential **out,
 	const char *username,
 	const char *publickey,
 	size_t publickey_len,
-	git_cred_sign_cb sign_callback,
+	git_credential_sign_cb sign_callback,
 	void *payload);
 
 /** @} */
diff --git a/include/git2/credential_helpers.h b/include/git2/credential_helpers.h
new file mode 100644
index 000000000..9a70ecb38
--- /dev/null
+++ b/include/git2/credential_helpers.h
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_git_credential_helpers_h__
+#define INCLUDE_git_credential_helpers_h__
+
+#include "transport.h"
+
+/**
+ * @file git2/credential_helpers.h
+ * @brief Utility functions for credential management
+ * @defgroup git_credential_helpers credential management helpers
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * Payload for git_credential_userpass_plaintext.
+ */
+typedef struct git_credential_userpass_payload {
+	const char *username;
+	const char *password;
+} git_credential_userpass_payload;
+
+
+/**
+ * Stock callback usable as a git_credential_acquire_cb.  This calls
+ * git_cred_userpass_plaintext_new unless the protocol has not specified
+ * `GIT_CREDENTIAL_USERPASS_PLAINTEXT` as an allowed type.
+ *
+ * @param out The newly created credential object.
+ * @param url The resource for which we are demanding a credential.
+ * @param user_from_url The username that was embedded in a "user\@host"
+ *                          remote url, or NULL if not included.
+ * @param allowed_types A bitmask stating which credential types are OK to return.
+ * @param payload The payload provided when specifying this callback.  (This is
+ *        interpreted as a `git_credential_userpass_payload*`.)
+ */
+GIT_EXTERN(int) git_credential_userpass(
+		git_credential **out,
+		const char *url,
+		const char *user_from_url,
+		unsigned int allowed_types,
+		void *payload);
+
+/** @} */
+GIT_END_DECL
+#endif
diff --git a/include/git2/deprecated.h b/include/git2/deprecated.h
index 7eb21dc9c..61d0115fd 100644
--- a/include/git2/deprecated.h
+++ b/include/git2/deprecated.h
@@ -33,6 +33,8 @@
 #include "status.h"
 #include "submodule.h"
 #include "worktree.h"
+#include "credential.h"
+#include "credential_helpers.h"
 
 /*
  * Users can avoid deprecated functions by defining `GIT_DEPRECATE_HARD`.
@@ -359,7 +361,7 @@ GIT_EXTERN(int) git_tag_create_frombuffer(
 
 /**@}*/
 
-/** @name Deprecated Credential Callback Types
+/** @name Deprecated Credential Types
  *
  * These types are retained for backward compatibility.  The newer
  * versions of these values should be preferred in all new code.
@@ -368,8 +370,77 @@ GIT_EXTERN(int) git_tag_create_frombuffer(
  * this time.
  */
 
-typedef git_cred_sign_cb git_cred_sign_callback;
-typedef git_cred_ssh_interactive_cb git_cred_ssh_interactive_callback;
+typedef git_credential git_cred;
+typedef git_credential_userpass_plaintext git_cred_userpass_plaintext;
+typedef git_credential_username git_cred_username;
+typedef git_credential_default git_cred_default;
+typedef git_credential_ssh_key git_cred_ssh_key;
+typedef git_credential_ssh_interactive git_cred_ssh_interactive;
+typedef git_credential_ssh_custom git_cred_ssh_custom;
+
+typedef git_credential_acquire_cb git_cred_acquire_cb;
+typedef git_credential_sign_cb git_cred_sign_callback;
+typedef git_credential_sign_cb git_cred_sign_cb;
+typedef git_credential_ssh_interactive_cb git_cred_ssh_interactive_callback;
+typedef git_credential_ssh_interactive_cb git_cred_ssh_interactive_cb;
+
+#define git_credtype_t git_credential_t
+
+#define GIT_CREDTYPE_USERPASS_PLAINTEXT GIT_CREDENTIAL_USERPASS_PLAINTEXT
+#define GIT_CREDTYPE_SSH_KEY GIT_CREDENTIAL_SSH_KEY
+#define GIT_CREDTYPE_SSH_CUSTOM GIT_CREDENTIAL_SSH_CUSTOM
+#define GIT_CREDTYPE_DEFAULT GIT_CREDENTIAL_DEFAULT
+#define GIT_CREDTYPE_SSH_INTERACTIVE GIT_CREDENTIAL_SSH_INTERACTIVE
+#define GIT_CREDTYPE_USERNAME GIT_CREDENTIAL_USERNAME
+#define GIT_CREDTYPE_SSH_MEMORY GIT_CREDENTIAL_SSH_MEMORY
+
+GIT_EXTERN(void) git_cred_free(git_credential *cred);
+GIT_EXTERN(int) git_cred_has_username(git_credential *cred);
+GIT_EXTERN(const char *) git_cred_get_username(git_credential *cred);
+GIT_EXTERN(int) git_cred_userpass_plaintext_new(
+	git_credential **out,
+	const char *username,
+	const char *password);
+GIT_EXTERN(int) git_cred_default_new(git_credential **out);
+GIT_EXTERN(int) git_cred_username_new(git_credential **out, const char *username);
+GIT_EXTERN(int) git_cred_ssh_key_new(
+	git_credential **out,
+	const char *username,
+	const char *publickey,
+	const char *privatekey,
+	const char *passphrase);
+GIT_EXTERN(int) git_cred_ssh_key_memory_new(
+	git_credential **out,
+	const char *username,
+	const char *publickey,
+	const char *privatekey,
+	const char *passphrase);
+GIT_EXTERN(int) git_cred_ssh_interactive_new(
+	git_credential **out,
+	const char *username,
+	git_credential_ssh_interactive_cb prompt_callback,
+	void *payload);
+GIT_EXTERN(int) git_cred_ssh_key_from_agent(
+	git_credential **out,
+	const char *username);
+GIT_EXTERN(int) git_cred_ssh_custom_new(
+	git_credential **out,
+	const char *username,
+	const char *publickey,
+	size_t publickey_len,
+	git_credential_sign_cb sign_callback,
+	void *payload);
+
+/* Deprecated Credential Helper Types */
+
+typedef git_credential_userpass_payload git_cred_userpass_payload;
+
+GIT_EXTERN(int) git_cred_userpass(
+	git_credential **out,
+	const char *url,
+	const char *user_from_url,
+	unsigned int allowed_types,
+	void *payload);
 
 /**@}*/
 
diff --git a/include/git2/proxy.h b/include/git2/proxy.h
index f959ae2e2..653425dee 100644
--- a/include/git2/proxy.h
+++ b/include/git2/proxy.h
@@ -10,7 +10,7 @@
 #include "common.h"
 
 #include "cert.h"
-#include "cred.h"
+#include "credential.h"
 
 GIT_BEGIN_DECL
 
@@ -61,7 +61,7 @@ typedef struct {
 	 * Returning GIT_PASSTHROUGH will make libgit2 behave as
 	 * though this field isn't set.
 	 */
-	git_cred_acquire_cb credentials;
+	git_credential_acquire_cb credentials;
 
 	/**
 	 * If cert verification fails, this will be called to let the
diff --git a/include/git2/remote.h b/include/git2/remote.h
index f9454d6d5..54b6672b9 100644
--- a/include/git2/remote.h
+++ b/include/git2/remote.h
@@ -517,7 +517,7 @@ struct git_remote_callbacks {
 	 * Returning GIT_PASSTHROUGH will make libgit2 behave as
 	 * though this field isn't set.
 	 */
-	git_cred_acquire_cb credentials;
+	git_credential_acquire_cb credentials;
 
 	/**
 	 * If cert verification fails, this will be called to let the
diff --git a/include/git2/sys/cred.h b/include/git2/sys/cred.h
index 7636e79e4..4d2a59af7 100644
--- a/include/git2/sys/cred.h
+++ b/include/git2/sys/cred.h
@@ -7,84 +7,9 @@
 #ifndef INCLUDE_sys_git_cred_h__
 #define INCLUDE_sys_git_cred_h__
 
-#include "git2/common.h"
-#include "git2/cred.h"
-
-/**
- * @file git2/sys/cred.h
- * @brief Git credentials low-level implementation
- * @defgroup git_cred Git credentials low-level implementation
- * @ingroup Git
- * @{
- */
-GIT_BEGIN_DECL
-
-/**
- * The base structure for all credential types
- */
-struct git_cred {
-	git_credtype_t credtype; /**< A type of credential */
-
-	/** The deallocator for this type of credentials */
-	void GIT_CALLBACK(free)(git_cred *cred);
-};
-
-/** A plaintext username and password */
-struct git_cred_userpass_plaintext {
-	git_cred parent; /**< The parent cred */
-	char *username; /**< The username to authenticate as */
-	char *password; /**< The password to use */
-};
-
-/** Username-only credential information */
-struct git_cred_username {
-	git_cred parent; /**< The parent cred */
-	char username[1]; /**< The username to authenticate as */
-};
-
-/**
- * A ssh key from disk
- */
-struct git_cred_ssh_key {
-	git_cred parent; /**< The parent cred */
-	char *username; /**< The username to authenticate as */
-	char *publickey; /**< The path to a public key */
-	char *privatekey; /**< The path to a private key */
-	char *passphrase; /**< Passphrase used to decrypt the private key */
-};
-
-/**
- * Keyboard-interactive based ssh authentication
- */
-struct git_cred_ssh_interactive {
-	git_cred parent; /**< The parent cred */
-	char *username; /**< The username to authenticate as */
-
-	/**
-	 * Callback used for authentication.
-	 */
-	git_cred_ssh_interactive_cb prompt_callback;
-
-	void *payload; /**< Payload passed to prompt_callback */
-};
-
-/**
- * A key with a custom signature function
- */
-struct git_cred_ssh_custom {
-	git_cred parent; /**< The parent cred */
-	char *username; /**< The username to authenticate as */
-	char *publickey; /**< The public key data */
-	size_t publickey_len; /**< Length of the public key */
-
-	/**
-	 * Callback used to sign the data.
-	 */
-	git_cred_sign_cb sign_callback;
-
-	void *payload; /**< Payload passed to prompt_callback */
-};
-
-GIT_END_DECL
+/* These declarations have moved. */
+#ifndef GIT_DEPRECATE_HARD
+# include "git2/sys/credential.h"
+#endif
 
 #endif
diff --git a/include/git2/sys/credential.h b/include/git2/sys/credential.h
new file mode 100644
index 000000000..bb4c9f942
--- /dev/null
+++ b/include/git2/sys/credential.h
@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) the libgit2 contributors. All rights reserved.
+ *
+ * This file is part of libgit2, distributed under the GNU GPL v2 with
+ * a Linking Exception. For full terms see the included COPYING file.
+ */
+#ifndef INCLUDE_sys_git_credential_h__
+#define INCLUDE_sys_git_credential_h__
+
+#include "git2/common.h"
+#include "git2/credential.h"
+
+/**
+ * @file git2/sys/cred.h
+ * @brief Git credentials low-level implementation
+ * @defgroup git_credential Git credentials low-level implementation
+ * @ingroup Git
+ * @{
+ */
+GIT_BEGIN_DECL
+
+/**
+ * The base structure for all credential types
+ */
+struct git_credential {
+	git_credential_t credtype; /**< A type of credential */
+
+	/** The deallocator for this type of credentials */
+	void GIT_CALLBACK(free)(git_credential *cred);
+};
+
+/** A plaintext username and password */
+struct git_credential_userpass_plaintext {
+	git_credential parent; /**< The parent credential */
+	char *username;        /**< The username to authenticate as */
+	char *password;        /**< The password to use */
+};
+
+/** Username-only credential information */
+struct git_credential_username {
+	git_credential parent; /**< The parent credential */
+	char username[1];      /**< The username to authenticate as */
+};
+
+/**
+ * A ssh key from disk
+ */
+struct git_credential_ssh_key {
+	git_credential parent; /**< The parent credential */
+	char *username;        /**< The username to authenticate as */
+	char *publickey;       /**< The path to a public key */
+	char *privatekey;      /**< The path to a private key */
+	char *passphrase;      /**< Passphrase to decrypt the private key */
+};
+
+/**
+ * Keyboard-interactive based ssh authentication
+ */
+struct git_credential_ssh_interactive {
+	git_credential parent; /**< The parent credential */
+	char *username;        /**< The username to authenticate as */
+
+	/**
+	 * Callback used for authentication.
+	 */
+	git_credential_ssh_interactive_cb prompt_callback;
+
+	void *payload;         /**< Payload passed to prompt_callback */
+};
+
+/**
+ * A key with a custom signature function
+ */
+struct git_credential_ssh_custom {
+	git_credential parent; /**< The parent credential */
+	char *username;        /**< The username to authenticate as */
+	char *publickey;       /**< The public key data */
+	size_t publickey_len;  /**< Length of the public key */
+
+	/**
+	 * Callback used to sign the data.
+	 */
+	git_credential_sign_cb sign_callback;
+
+	void *payload;         /**< Payload passed to prompt_callback */
+};
+
+GIT_END_DECL
+
+#endif
diff --git a/include/git2/sys/transport.h b/include/git2/sys/transport.h
index d7c7313af..6cee42f54 100644
--- a/include/git2/sys/transport.h
+++ b/include/git2/sys/transport.h
@@ -55,7 +55,7 @@ struct git_transport {
 	int GIT_CALLBACK(connect)(
 		git_transport *transport,
 		const char *url,
-		git_cred_acquire_cb cred_acquire_cb,
+		git_credential_acquire_cb cred_acquire_cb,
 		void *cred_acquire_payload,
 		const git_proxy_options *proxy_opts,
 		int direction,
@@ -266,7 +266,7 @@ GIT_EXTERN(int) git_transport_smart_certificate_check(git_transport *transport,
  *         refused to provide credentials and callers should behave as if no
  *         callback was set), or < 0 for an error
  */
-GIT_EXTERN(int) git_transport_smart_credentials(git_cred **out, git_transport *transport, const char *user, int methods);
+GIT_EXTERN(int) git_transport_smart_credentials(git_credential **out, git_transport *transport, const char *user, int methods);
 
 /**
  * Get a copy of the proxy options
diff --git a/include/git2/transport.h b/include/git2/transport.h
index b99bb30e1..fc99ce8f3 100644
--- a/include/git2/transport.h
+++ b/include/git2/transport.h
@@ -11,7 +11,7 @@
 #include "net.h"
 #include "types.h"
 #include "cert.h"
-#include "cred.h"
+#include "credential.h"
 
 /**
  * @file git2/transport.h