Securing encoding data slices using an integrity check value list

1. A method comprises:

retrieving, by a computing device of a dispersed storage network (DSN) or another computing device of the DSN, a read threshold number of integrity check value list (ICVL) encoded data slices of a set of ICVL encoded data slices from at least some storage units of a set of storage units;

determining, by the computing device or the other computing device, whether an appended ICVL of each ICVL encoded data slice of the read threshold number of ICVL encoded data slices substantially match;

when the appended ICVL of one of the ICVL encoded data slices of the read threshold number of ICVL encoded data slices does not substantially match the appended ICVL of other ICVL encoded data slices of the read threshold number of ICVL encoded data slices:

determining, by the computing device or the other computing device, a likely cause for the appended ICVL of the one of the ICVL encoded data slices not substantially matching the appended ICVL of the other ICVL encoded data slices; and

when the likely cause is missing a revision update:

initiating, by the computing device or the other computing device, rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generating, by the computing device or the other computing device, an integrity check value for the rebuilt encoded data slice;

generating, by the computing device or the other computing device, an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

appending, by the computing device or the other computing device, the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

sending, by the computing device or the other computing device, the rebuilt ICVL encoded data slice to one of the storage units of the set of storage units for storage therein.

2. The method of claim 1 further comprises:

generating, by the computing device, a set of integrity check values for a set of encoded data slices, wherein a data segment of a data object is dispersed storage error encoded to produce the set of encoded data slices;

generating, by the computing device, an integrity check value list from the set of integrity check values;

appending, by the computing device, the integrity check value list (ICVL) to each encoded data slice of the set of encoded data slices to produce a set of ICVL encoded data slices; and

sending, by the computing device, the set of ICVL encoded data slices to the set of storage units of the DSN for storage therein.

3. The method of claim 1 further comprises:

when the likely cause is an inaccurate integrity check value list (ICVL) appended to the one of the ICVL encoded data slices:

calculating a new integrity check value for an encoded data slice portion of the one of the ICVL encoded data slices;

extracting the integrity check value from the appended ICVL of one of the other ICVL encoded data slices to produce an extracted integrity check value;

comparing the new integrity check value with the extracted integrity check value; and

when the new integrity check value substantially matches the extracted integrity check value, utilizing the encoded data slice in decoding of the read threshold number of encoded data slices to recover the data segment.

4. The method of claim 3 further comprises:

when the new integrity check value does not substantially match the extracted integrity check value:

initiating, by the computing device or the other computing device, rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generating, by the computing device or the other computing device, an integrity check value for the rebuilt encoded data slice;

generating, by the computing device or the other computing device, an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

appending, by the computing device or the other computing device, the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

sending, by the computing device or the other computing device, the rebuilt ICVL encoded data slice one of the storage units of the set of storage units for storage therein.

5. The method of claim 1 further comprises:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices, sending, by the computing device or the other computing device, a delete message to a storage unit storing the one of the ICVL encoded data slices to delete the one of the ICVL encoded data slices.

6. The method of claim 1 further comprises:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices:

initiating, by the computing device or the other computing device, rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generating, by the computing device or the other computing device, an integrity check value for the rebuilt encoded data slice;

generating, by the computing device or the other computing device, an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

appending, by the computing device or the other computing device, the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

sending, by the computing device or the other computing device, the rebuilt ICVL encoded data slice one of the storage units of the set of storage units for storage therein.

7. The method of claim 1 further comprises:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices, determining, by the computing device or the other computing device, whether other encoded data slices stored by a storage unit storing the one of the ICVL encoded data slices have been modified in an unauthorized manner; and

when the other encoded data slices stored by the storage unit have been modified in the unauthorized manner, initiating, by the computing device or the other computing device, at least one of a decommissioning of the storage unit, a quarantine of the storage unit, and a higher level of security regarding access to the storage unit.

8. A computer readable memory comprises:

a first memory element that stores operational instructions that, when executed by a computing device of a dispersed storage network (DSN) or another computing device of the DSN, causes the computing device or the other computing device to:

retrieve a read threshold number of integrity check value list (ICVL) encoded data slices of a set of ICVL encoded data slices from at least some storage units of a set of storage units;

determine whether an appended ICVL of each ICVL encoded data slice of the read threshold number of ICVL encoded data slices substantially match;

when the appended ICVL of one of the ICVL encoded data slices of the read threshold number of ICVL encoded data slices does not substantially match the appended ICVL of other ICVL encoded data slices of the read threshold number of ICVL encoded data slices, determine a likely cause for the appended ICVL of the one of the ICVL encoded data slices not substantially matching the appended ICVL of the other ICVL encoded data slices;

a second memory element that stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the likely cause is missing a revision update:

initiate rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generate an integrity check value for the rebuilt encoded data slice;

generate an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

append the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

send the rebuilt ICVL encoded data slice to one of the storage units of the set of storage units for storage therein.

9. The computer readable memory of claim 8 further comprises:

a third memory element that stores operational instructions that, when executed by the computing device, causes the computing device to:

generate a set of integrity check values for a set of encoded data slices, wherein a data segment of a data object is dispersed storage error encoded to produce the set of encoded data slices;

generate an integrity check value list from the set of integrity check values;

append the integrity check value list (ICVL) to each encoded data slice of the set of encoded data slices to produce a set of ICVL encoded data slices; and

send the set of ICVL encoded data slices to the set of storage units of the DSN for storage therein.

10. The computer readable memory of claim 8 further comprises:

a third memory element that stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the likely cause is an inaccurate integrity check value list (ICVL) appended to the one of the ICVL encoded data slices:

calculate a new integrity check value for an encoded data slice portion of the one of the ICVL encoded data slices;

extract the integrity check value from the appended ICVL of one of the other ICVL encoded data slices to produce an extracted integrity check value;

compare the new integrity check value with the extracted integrity check value; and

when the new integrity check value substantially matches the extracted integrity check value, utilize the encoded data slice in decoding of the read threshold number of encoded data slices to recover the data segment.

11. The computer readable memory of claim 10 , wherein the third memory element further stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the new integrity check value does not substantially match the extracted integrity check value:

initiate rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generate an integrity check value for the rebuilt encoded data slice;

generate an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

append the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

send the rebuilt ICVL encoded data slice one of the storage units of the set of storage units for storage therein.

12. The computer readable memory of claim 8 further comprises:

a third memory element that stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices, send a delete message to a storage unit storing the one of the ICVL encoded data slices to delete the one of the ICVL encoded data slices.

13. The computer readable memory of claim 8 further comprises:

a third memory element that stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices:

initiate rebuilding of the encoded data slice portion of the one of the ICVL encoded data slices to produce a rebuilt encoded data slice;

generate an integrity check value for the rebuilt encoded data slice;

generate an updated integrity check value list including the integrity check value for the rebuilt encoded data slice and integrity check values of the encoded data slices of the other ICVL encoded data slices;

append the updated integrity check value list to the rebuilt encoded data slice to produce a rebuild ICVL encoded data slice; and

send the rebuilt ICVL encoded data slice one of the storage units of the set of storage units for storage therein.

14. The computer readable memory of claim 8 further comprises:

a third memory element that stores operational instructions that, when executed by the computing device or the computing device, causes the computing device or the other computing device to:

when the likely cause is an unauthorized modification of the one of the ICVL encoded data slices, determine whether other encoded data slices stored by a storage unit storing the one of the ICVL encoded data slices have been modified in an unauthorized manner; and

when the other encoded data slices stored by the storage unit have been modified in the unauthorized manner, initiate at least one of a decommissioning of the storage unit, a quarantine of the storage unit, and a higher level of security regarding access to the storage unit.