---
name: "Fapi_ChangeAuth"
section: "3"
platform: "linux"
package: "tpm2-tss"
version: "4.2.0-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/Fapi_ChangeAuth"
---

# Fapi\_ChangeAuth(3)

Fapi\_ChangeAuth

## NAME

Fapi\_ChangeAuth - Fapi\_ChangeAuth

## SYNOPSIS

### Functions

TSS2\_RC **Fapi\_ChangeAuth** (**FAPI\_CONTEXT** \*context, char const \*entityPath, char const \*authValue)\
 TSS2\_RC **Fapi\_ChangeAuth\_Async** (**FAPI\_CONTEXT** \*context, char const \*entityPath, char const \*authValue)\
 TSS2\_RC **Fapi\_ChangeAuth\_Finish** (**FAPI\_CONTEXT** \*context)\

## Detailed Description

FAPI functions to invoke ChangeAuth either as one-call or in an asynchronous manner.

## Function Documentation

### TSS2\_RC Fapi\_ChangeAuth (FAPI\_CONTEXT \* context, char const \* entityPath, char const \* authValue)

One-Call function for Fapi\_ChangeAuth

Changes the Authorization data of an entity found at keyPath. The parameter authValue is a 0-terminated UTF-8 encoded password. If it is longer than the digest size of the entity's nameAlg, it will be hashed according the the TPM specification part 1, rev 138, section 19.6.4.3.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *entityPath* The path to the entity to modify \
 *authValue* The new 0-terminated password to set for the entity. May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context or entityPath is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_PATH* if entityPath does not map to a FAPI entity. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_NO\_TPM* if FAPI was initialized in no-TPM-mode via its config file. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *TSS2\_FAPI\_RC\_PATH\_NOT\_FOUND* if a FAPI object path was not found during authorization. \
 *TSS2\_FAPI\_RC\_KEY\_NOT\_FOUND* if a key was not found. \
 *TSS2\_FAPI\_RC\_TRY\_AGAIN* if an I/O operation is not finished yet and this function needs to be called again. \
 *TSS2\_FAPI\_RC\_GENERAL\_FAILURE* if an internal error occurred. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_UNKNOWN* if a required authorization callback is not set. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_FAILED* if the authorization attempt fails. \
 *TSS2\_FAPI\_RC\_POLICY\_UNKNOWN* if policy search for a certain policy digest was not successful. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned.

### TSS2\_RC Fapi\_ChangeAuth\_Async (FAPI\_CONTEXT \* context, char const \* entityPath, char const \* authValue)

Asynchronous function for Fapi\_ChangeAuth

Changes the Authorization data of an entity found at keyPath. The parameter authValue is a 0-terminated UTF-8 encoded password. If it is longer than the digest size of the entity's nameAlg, it will be hashed according the the TPM specification part 1, rev 138, section 19.6.4.3.

Call Fapi\_ChangeAuth\_Finish to finish the execution of this command.

**Parameters**

*context* The **FAPI\_CONTEXT** \
 *entityPath* The path to the entity to modify \
 *authValue* The new 0-terminated password to set for the entity. May be NULL

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context or entityPath is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_PATH* if entityPath does not map to a FAPI entity. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *TSS2\_FAPI\_RC\_NO\_TPM* if FAPI was initialized in no-TPM-mode via its config file. \
 *TSS2\_FAPI\_RC\_PATH\_NOT\_FOUND* if a FAPI object path was not found during authorization. \
 *TSS2\_FAPI\_RC\_KEY\_NOT\_FOUND* if a key was not found. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned.

### TSS2\_RC Fapi\_ChangeAuth\_Finish (FAPI\_CONTEXT \* context)

Asynchronous finish function for Fapi\_ChangeAuth

This function should be called after a previous Fapi\_ChangeAuth\_Async.

**Parameters**

*context* The **FAPI\_CONTEXT**

**Return values**

*TSS2\_RC\_SUCCESS* if the function call was a success. \
 *TSS2\_FAPI\_RC\_BAD\_REFERENCE* if context is NULL. \
 *TSS2\_FAPI\_RC\_BAD\_CONTEXT* if context corruption is detected. \
 *TSS2\_FAPI\_RC\_BAD\_SEQUENCE* if the context has an asynchronous operation already pending. \
 *TSS2\_FAPI\_RC\_IO\_ERROR* if the data cannot be saved. \
 *TSS2\_FAPI\_RC\_MEMORY* if the FAPI cannot allocate enough memory for internal operations or return parameters. \
 *TSS2\_FAPI\_RC\_TRY\_AGAIN* if the asynchronous operation is not yet complete. Call this function again later. \
 *TSS2\_FAPI\_RC\_BAD\_VALUE* if an invalid value was passed into the function. \
 *TSS2\_FAPI\_RC\_GENERAL\_FAILURE* if an internal error occurred. \
 *TSS2\_FAPI\_RC\_PATH\_NOT\_FOUND* if a FAPI object path was not found during authorization. \
 *TSS2\_FAPI\_RC\_KEY\_NOT\_FOUND* if a key was not found. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_UNKNOWN* if a required authorization callback is not set. \
 *TSS2\_FAPI\_RC\_AUTHORIZATION\_FAILED* if the authorization attempt fails. \
 *TSS2\_FAPI\_RC\_POLICY\_UNKNOWN* if policy search for a certain policy digest was not successful. \
 *TSS2\_ESYS\_RC\_\** possible error codes of ESAPI. \
 *TSS2\_FAPI\_RC\_NOT\_PROVISIONED* FAPI was not provisioned. \
 *TSS2\_FAPI\_RC\_BAD\_PATH* if the path is used in inappropriate context or contains illegal characters.

## Author

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